I couldn’t do my job without a computer and the internet.
I can, and often do, bike to work. I’d miss video games terribly and probably resort to playing paper games. But I can’t do without the Internet.
As Trom just said, there are some of us who couldn’t do their jobs without a computer.
I mean, after all, I write code for a living.
That is really really hard to do without a computer, though I suppose I could write a lot of stuff on paper. Actually, I could get by with a whiteboard and paper and pens for a few days if I dedicated myself to designing.
Without a car, I would have to get a hotel room near the lab and use their shuttle.
I could actually get by without the Internet for a while. Sometimes I have to when I am on-site somewhere. Not every site allows Internet access to an outsider, and sometimes the hotel’s free access is either down or dial-up speed.
It depends. I could easily give up all of the things listed if I was going to be plunked down in a beach resort with no worries about work or family.
Car.
My job would force me to use computers/internet, so that one is out. OTOH, how would I get to work/grocery store/etc?
However, of all technological things to give up for a month the most difficult would be (depending on the month, of course):
Air Conditioning. I’ve lived in Georgia and Texas most of my life and it truly is a wonderful thing, that conditioned air. 
For me, it would be the computer/Internet.
Luckily, I can telecommute to work, and although I live in the suburbs, I’m only about a 5-10 minute bike ride from three different strip malls. As for the cell phone, I’d love to give that up for a month. The only time I ever hear the damn thing, it’s ringing!
My job is unreachable except by car ( out in the middle of an unincorporated, non-residential area ), so by default that would create more hardship than anything else.
Though loss of my computer would be quite annoying for my daily routine, I don’t miss it at all while on vacations and could make do. Television/video games would rank lower and cell phones would be on the bottom.They’re convenient, but I still have a landline and don’t usually need one.
Of the listed choices, computer and internet would be the hardest to give up. If you count modern plumbing as technological, it would win by an obscene margin.
Since I don’t have a cellphone, car or video games, that narrows it down a bit.
I actually do go without everything on your list except computer/internet.
No computer = no job for me, so this is easy. No car means I’d have to depend on my SO for rides and that would suck, but no paycheck would suck a lot more.
However, I’m with Athena…my first thought was “hot running water”. No shower in the morning and the rest of my day is going to suck no matter what I’m doing.
I picked Internet. It is my main form of social communication and entertainment.
Cell phone - I hate talking on the phone, so I only use it when I have to.
Car - Shopping for anything can be done on the internet, including ordering groceries from the store nearby that has same-day delivery.
Television - I like TV, but my life would be just as okay without it.
Video Games - I rarely play them, but OTH, that is what the Internet is for, right?
Without internet, how am I going to look at porn?
What?! Somebody had to say it 
I drive over 600 miles a week there is no way I could do my job without a car. If I didn’t have to work I could survive in my town with just my bike so the internet would probably be number two because I could watch the TV I’m missing on the net. I mainly use my cell phone for web-surfing anyhow and I could use Skype or similar for any phone calls I needed to make.
That being said until about a month ago I didn’t have internet except at work or occasionally on my phone and I really didn’t miss it.
I voted Computer/Internet, but since I’m a WoW addict, I’d kind of need to have the video game part of it too, since I couldn’t have WoW without the computer and the internet.
I don’t think a car belongs in the poll because it’s a necessary function. It would be like giving up running water. The rest of the choices are not vital to survival so I chose the internet because it replaces everything else. It serves as a phone, media and game player because of all the free aps on the internet.
I suppose it also replaces the car because I could order everything delivered and work from home with the right job.
I’m not old enough to remember when there weren’t cars but my parents were. I consider none of the above “necessary to survival,” Magiver, and am chuckling at our different perspectives.
In fact, as a bit of a NeoLuddite, I consider all of the above both a blessing and a curse on civilization.
What I have the most difficulty living without is my motorcycle and during the Winter months I’m pining away for it. It’s my favorite form of R&R.
Second closest is the computer. It’s like having the world’s libraries at my fingertips.
Edit: There were cars in my parents’ lifetimes but they were more of a novelty of the wealthy or a very pricy convenience when my parents were little.
If it wasn’t something done against my will I could easily go without any of them for a month - I’m making that distinction as compared to, say, having to do my job (IT) without internet access or my Blackberry.
I suppose that I’d miss internet access the most just out of force of habit but when I go backpacking it only takes a few hours to get used to not having all that crap along.
I’ve got a bike with cargo rack so shopping isn’t hard. The Bay Area has plenty of mass transit (I don’t need a car day to day at all, for example I do not need it to commute) so visiting friends who don’t live nearby is no problem.
Video games, meh. Every so often I’m in a gaming phase but it’s been a few years since anything lit my fire, gamewise. Ditto with TV, there’s very little that I make a point of watching and not seeing it for a month wouldn’t bother me.
Unlike Athena I happen to enjoy washing dishes, haven’t had a dishwasher in 8 years or so.
I picked computer, but I should have picked car. I can’t get to work without it.
Difficult. I rarely play video games, so that’s no biggie. I could live without the cell phone if I absolutely had to. TV would be difficult, but I’d manage.
That leaves the last two, car and C&I. Without a car I couldn’t get to work. If I did have the car but gave up C&I then once I got to work I couldn’t do anything, since I work in IT. So not using either one would likely lead to me being unemployed. 