Memory usage has shot up

Hi everyone - long time lurker on TomsHardware...I visit the main site frequently but never tried signing up here. Now, I've got a problem.

My memory usage has shot up. I've tried running two programs to see if it's malware (Spybot Search and Destroy and AVG) and they both came up with nothing and didn't help out.



As you can see, not many programs are being run, but my usage (see the sidebar) is at 80%.

It all happened when I tried to download a program called "TrueCrypt". My computer was absolutely fine before that.

Here are my specs:

E6600 @ 3.2 GHz
2 GB DDR2-800 Patriot Extreme Performance (although I ordered a set of OCZ 4GB DDR2-800 Reaper edition just in case it's the actual memory)
EVGA 680i LT SLi
Windows Vista Home Premium 64 bit
EVGA 8800 GTX
150 GB Raptor (on which the OS is on)
250 GB Caviar

One other question - should I need to reformat, all I really need is my stuff from iTunes, so I don't really need to worry about backing up anything else. However, I only have an OEM copy of Vista Home Premium, so if I tried to install it after a format, would it still work?

Thanks everyone and I appreciate any future replies. If this is in the wrong section by any chance, I apologize.

Oh, yeah. I do have SP1.

But I've had it for over a month or so (since it's release, whenever it was) and my PC has been fine.

Now it just...well, the OP says what it does.

I uninstalled TrueCrypt though.

Memory usage was OK for 2 gigs on Vista 64 bit - hovered around 50-60% with Firefox, AIM, mIRC and iTunes up.

Now, iTunes won't even run and Firefox crashes atleast once an hour with an error message, and I have no sound on any videos.