You don’t need to buy antivirus protection. You can get it free.
AVS / Avast are excellent. Spybot and Malwarebytes are good too. Microsoft Security Essentials often find things the others miss and you have Windows Defender.
You should have AVS or Avast and probably Malwarebytes or Spybot too.
Windows 7 is excellent. You probably want to go with the 64 bit version, unless you have a good reason not to. Like you have software that won’t run on 32 bit.
If you have the 64 bit version of Win7 you can have more than 4g of memory. Actually the 32 bit only uses about 3g to 3.5g of memory even if you have 4g installed.
How much you need is what you use the computer for. For most people 4g is enough but if you do a lot of gaming or video editing, you will find you need more.
The bigger the cache the quicker the computer can access what’s stored in it. Again how much you need depends on what you need.
The key thing is write down what you are going to use your computer for, then buy your computer around that.
For laptops, if you order online, you have to go into a store and look at the one you’re going to order. This is really important.
First of all weight is essential. Everyone has a different tolerance for how much their laptop should weigh. You need to physically pick it up and feel it and see how it feels to you
Second you need to type on it. Different laptops have different keyboard. My laptop doesn’t have a number pad, I miss that a lot. Yeah I know you can buy a number pad and plug it in, but I know the next laptop I get will have a number pad on it.
Third you need to check out the screen. Again this is just a personal preference. Some screens present things a bit different. It’s not good or bad it’s just a matter of what you like.
Fourth consider things like, do I have enough USB ports? Or do I need an external modem?
Things I would get is a eSATA port. Most laptops don’t have them, but if you’re getting an external hard drive to compliment your laptop an eSATA port blows a USB port away
Also I have a built in digital TV tuner to my laptop and I love it. That is something that you may or may not want.
When you revist this thread tell others what you want to do with your computer, especially if you’re a gamer. Then the others who are into that (especially if you seriously play games) can tell you specifically what you’ll need.