Somehow my laptop is now using almost all of its available disc space: I tried the normal clean-up routine, but that freed up a minuscule amount. I have tried poking around in Explore mode but since almost all disc space is gone it takes forever to open up a folder, and then a directory, and then a file…
Is there a quick way to review what programs or files are consuming the most hard disk space?
I have used a program called Space Monger, which graphically represents all the folders on your hard drive as a box; the larger the box, the more data it contains. It will help you spot space hogs.
Have you tried uninstalling unused applications? Right click on your Program Files folder, and see how much space it is taking up.
Assuming you’re using Windows XP, you can view a list of programs by size by going to Control Panel -> Add or Remove Programs, then in the “Sort by:” drop-down menu in the upper right, selecting “Size”. You can then use this same utility to remove any programs you no longer use.
For individual files, your best bet is to start with any folders that you know contain large amounts of media files (video, audio, pictures, etc). If you have no idea where to start, the best thing I can advise without installing any more programs than you already have is:
ETA: If you don’t mind installing one more program, Fear Itself’s recommendation is a good one, and far less tedious than the process I described. 
Your link isn’t found by me. ** ETA: It connects now! Wait for update!**
I looked at program files and have tonnes of space remaining.
FYI: I had a virus lately that prevented me from connecting to the Internet with this laptop. I could connect to the router, but no Internet access was possible. Malware Bytes returned me to normalcy, except for the fact that my hard drive is maxed.
Help!
Your link isn’t working after all. 
Sixty-five.net seems to be down at the moment. Here’s a link to the CNet download page for the SpaceMonger utility.
Ain’t happenin’ for me?
screw saving space, just run out and get yourself an external hard drive. You can get a terrabyte drive for under $200 now. A freakin Terabyte! The future is now! 
QFT
I picked one up today for $149.
I am long overdue for a hard-drive wipe and reinstall. My computer is so filled with cruft it takes like 5 minutes from boot until it is responsive. Like a fool, I had been putting off a wipe for months now - rationalizing, eh, I have like 100 gb to back up. Burning 12-15 DVDs will take forever.
Everything I needed backed up - done in 2 hours. Beautiful. And the thing is only like 10% full.
If you’re running out of space, but the amount of space on your hard drive does not seem to be accounted for my all your Program and Windows and file folders, it could be that System Restore is the culprit.
System Restore sometimes uses a whole lot of space creating restore points, and sometimes it’s worth turning it off and starting it again, to get rid of all the old restore points. The main caveat, of course, is that erasing restore points means that, if something goes wrong now, you won’t have a previous restore point to go back to.
If your computer’s working OK, though, i think it’s worth it.
I’m a hopeless sucker for trying out all sorts of freeware programs, just to see if they’re any good, and then leaving them on my computer. After a while, things really start to slow down, and a little while ago i was having the same problem as you, with really slow startup times.
Then my external backup hard drive started making funny noises, so i got a new one and also decided to take the time to do a reinstall of the OS. Now that it doesn’t have all that extraneous crap on it, my 4+ year-old computer boots up nice and quickly again. It also helps to go in and disable all the unnecessary startup crap that some programs add to the system, because every useless extra thing slows down the startup process.
Seconded. Treesize is a great little program.
Okay…I have the solution for you, assuming you are using Windows XP. Check for a logfile called drwtsn32.log, and delete it. It’s just a mostly useless file that records any information about crashes, etc., on your computer…my routinely filled up all 200GB of my hard drive, until I learned to completely disable error logging. To prevent this from happening routinely, go into your system settings and tell it not to record any errors at all. In my case, no other setting would work to limit its size, and the file would just grow and grow until my hard drive became full.
Also, you should definitely turn off System Restore for all drives, especially since viruses may be hiding in there. In my opinion, you should also keep it off, since it’s a useless thing that bloats up your hard drive, and if you ever get a virus, you’ll probably have to disable it anyway, so backups won’t really be an option. But you can always re-enable it and monitor its size…to do this you have to enable the option to show hidden folders (I think you go to tools>folder options>view tab to find that menu).
I must disagree. System Restore just today saved me quite some work when installing MS Virtual Server borked my PC. And malware cannot hide in the System Restore area from an anti-malware product that has the correct security privileges.
With regard to System Restore, one thing the OP should do is use the VSSADMIN command to restrict the amount of space used.
There are too many people trying to help at once here so I will only make this point. You can adjust system restore to a more reasonable amount of disk usage. I only allocate about 1 Gig to it instead of the 4 Gig it uses automatically. It can use up to 12% of the hard drive. You don’t have to turn it off.
I recently bought a 1.5 TB drive for $160 (including tax). That’s 1,500,000,000,000 bytes.
OK, I got TreeSize to work and freed up a crap load of space.
Thanks.