Time to turn to toms!

Having a new, terribly annoying issue I can't get to the bottom of, so I need the tommies. Here's the system specs before I go on.

E6600 @ 2.88, has been to 3.42 stable
ASUS P5N32SLI-SE Deluxe
2gb ddr2 667
500gb Seagate Barracuda (~3 months old)
8800gtx
850w PSU
Win7 32bit

So, this machine has just started randomly hanging on me. Usually hangs for 10-15 seconds, then comes back like nothing happened. It happens randomly, sometimes at 30 second intervals, sometimes 30 minutes. It's most noted when running Mozilla, while opening a new tab, or when a video starts to play. I've noticed some games have slowed by 10fps or so. I've ran memtest for about 3 hours, 0 errors. My temps are average across the board, both cores 100% load around 52C, 43C idle. Now, I'm hearing a slight clicking noise in my PC randomly, most likely my drive, but I'm wondering if I'm just hearing it now, or if it's an actual drive failure imminent. According to Seagate Seatools, the drive reports no errors. I've also updated my nvidia drivers to the most current, because I first noticed this happening when any HD video was played, but I'm learning thats not the only trigger. Anything simple I'm missing here?

I think it's the psu problem too, if you got a generic 850watt from like coolmax,raidmax,etc. it could have horrible voltages given on the 12v or not enough amps

maybe add 2gb more ram ram is pretty cheap anyway

Dang. I was hoping it wouldn't come down to that, but I guess it's my motivation for going 64 bit and grabbing another 2gb of ram. By the way, I just ran Seatools as well as chkdsk again, still no errors, and it doesnt seem to be too bad today. Weird. I have a new update, that may or may not be relevant. I tried out that readyboost a few days ago, and although I noticed no difference in performance, could that have something to do with it?