Please help! Computer hangs. Wierd problem.

First of all Hello Hardware section, haven't posted outside of the "other" in ages.

My specs are:
e6400 @3200, stable oc
2gb corsair ram ddr2 800 stock
8800gts 640
rosewill 600w
1hdd wd 250gb 16mb sata (4partitions, 1 for os, 1 for apps, 1 for games, 1 for storage)
vista x32

Have been using this pc for a year and a half, about 8 months with vista and never had any problems. All of the sudden yesterday I get an vista message that I have about 56mb left on C drive (was 20gb partition). Pc slowed down and hanged. I have backup my data and installed clean vista, formatted all 4 partitions, resized C drive to 25gb.

After clean restore I get the same deal, vista seems to eat the c drive by itself. After install i had about 13gb free, few minutes later and i got 10gb free. While i understand that vista might use a lot of hdd for system restore etc., this has never happen before. If i try to download something from the web the download will hang at about 98-99% and will not complete, custom virus scan with eset is slow and hangs if i attempt to stop it. To recover from all this i have to pull the plug.

Could this be a hdd failure in progress? My pc is regularly scanned with latest "trojan remover" and eset nod32. And again, this literally happened for no apparent reason. What should I do?

so far I ran the quick test (with wd's diag tool) and it passed but I'm gonna try to run a full test in a little while.

The only solution is get a new hd and set for your system only, it is not the hd problem

Here's another thing I forgot to mention, whenever I try to copy a file from a usb stick the system also freezes, the similar thing happened when I've tried to scan the drive for bad sectors with wd's diag tool, it was scanning but I've noticed the unusually high use of ram, I have 2gigs, vista usually idles at around 600-700mb but when I started the scan vista started to increasingly use up to two gigs, I stopped the scan at 1900mbs, but it kept on rising and the hdd was constantly used even though I stopped the scan.

Does that sound like an hdd issue?

LMAO, nah I got an external one for my porn, in case I have to switch computers it's all there

Thanks for your advice but like I said if I'm going to buy a new one I'll go for 10k