Most efficient upgrade?

I'd like to get your (expert) opinions on the best way to spend 500-700 upgrading my PC. I currently have:

Asus A8nSLI Premium mobo
AMD Athlon X2 Dual Core 3800+ @ 2.0 ghz
Nvidia 7800 GT video card
2 gigs Corsair 400mhz Ram
40 gig (old) Western Digital HD -running my OS only right now
250 gig (new) Western Digital HD - storage

*Request advice on a new monitor, been using the same one since 2001. I would like to use it both for gaming and watching TV/movies from my bed (no more than 15 feet away or so).

I built this rig myself maybe 3 years ago, and got a great deal on the hardware thanks to you guys, but I'd like to upgrade a little. I would eventually like to build into a whole new computer and give this one to my little brother, so if we could do an upgrade now that I could add onto later to get a whole new system, that'd be ideal.

Thanks

 

new processor would be my #1 choice. since it's socket 939 and not AM2, you should be able to pick up a nice proc for really cheap, maybe check out an fx-62 if you can find one

2 gigs or RAM is fine if you're on XP, if you've got Vista then id get another gig or two.

You may or may not be happy with your 7800GT, if not then check out an 8800GT. anything less wouldnt be worth it IMO.

as far as monitors go, dont buy one if you havent seen it in person. go check some out at a local shop to see which one you like and then try to find it online for less money. it is impossible to judge the picture quality of a monitor just by reading the specs. oh, and for gaming, look into something with 8ms or less response time.

 

I like the look of that processor, I'll definitely put some serious thought into it. More immediately: how good of a deal is this?

I'm definitely in the market for an upgrade from a REALLY old CRT, but I'm almost tempted to go one notch higher to a 24" screen. If some of you could compare while I'm at work and let me know if you think there is something else I should be looking at I'd appreciate it. Thanks guys.

 

i wouldnt really recommend buying a monitor without seeing it in person. it is impossible to judge the picture quality just by seeing the specs, and what one person may consider good picture quality, another may not so the reviews arent really worth that much. if you want to get the black friday price, go ahead and buy it, Acer makes great stuff and apparently it won a customer choice award. im a total impulse buyer haha so i wouldnt hesitate, and im sure this would be a huge step up over an old CRT

 

Ok I'm getting the monitor, but one more quick question:

Asus A8nSLI Pro motherboard
Windows Vista Home Premium 32bit

Current memory is:
CORSAIR XMS 2GB (2 x 1GB) 184-Pin DDR SDRAM DDR 400 (PC 3200) Dual Channel

Question: Can someone just point me at some more (preferably Corsair) memory that will work along with my current hardware? What do I need to look for as far as compatibility? I'd like to order more tonight along with the monitor while I still have the guts to part with my hard-earned money, but the price for that particular kit above is still 184.00 which seems high because I bought it about 3 years ago.