As the title says.

This is assuming a decent core and a 1gig video card as well on a 64-bit OS. I remember a time when 2 gigs of DDR was a "sweet spot," but how does that translate to today's hardware and systems? Is more better? If so, how much? 6gigs? 8gigs? 12?

4 Gigs is plently for now (gaming wise that is). But if you would like to provide a bit of "future proofing" to your system and the fact that memory is so cheap these days (unless your on a really tight budget) I would consider going more than 4.

you can also create a RAMDrive for games that stream a lot of data from your HDD (Arma2, Fallout3, GTA4, etc.) which can give you a huge performance boost. It will basically pre-load the info into RAM and use it like a regular harddrive. I plan on getting another 4GB just for that if I can get enough funds saved up

More than four became popular with the i7 CPU since it supports tri-channel memory.

Exactly, but now Intel has returned to dual channel with its Lynnfield i7 and i5 processors, so is 4 or 8 the new norm for enthusiast desktops?

Come on guys...support the PC industry ....buy at least 6 gigs and always buy at least 2 of the best video cards ....3 better.

Hmmm... how do I create a RAMDrive? Is having lotsa memory enough, or do I have to flick some switches?

OK, I'm listening. If I buy 3 video cards, can I get a MOBO that supports all three?

Ripcord

lol...they make mobo's that support four!
The better question is what PSU to get that's will support everything and still be reliable lol

honestly unless you want to run the newest games @ max FPS (which really doesn't matter over 60FPS) with all the max visual settings. Having more then 4-6GB RAM and or more then 1-2 higher/highest end cards isn't worth the money.

If you are into playing older sim games you can get by easily with a 8800/9800 series Nvidia card or 47XX series ATI card.

Yes there are boards out there that support 8+ GB of RAM, usually triple set RAM, as well as up to 4 VGAs and even then those VGAs could be dual GPU cards however. Is it really really worth it? I cant' tell you not to spend your money, however like I said above, would it be worth the money?

Oh and something often over looked with multi VGA/GPU systems is the PSU being inadequate and often will cause problems with the system usually mistaken for a bad card, when if fact the card(s) fine, just not enough power to the system over all.

Having more then 2-4GB of system RAM can give you an increase in your FPS and over all quality of visual experience the amount of increase is different with each system do to so many variables. More then 4 (3.75GB) RAM comes into its own if you are running a 64bit OS, if you are still on 32bit, it doesn't hurt but doesn't help that much depending on how much system resources your OS is using already and for the average home PC user that isn't aware of things like that, their OS is easily using 40-60% of their total system RAM.

I run two systems (quad core duos with 4GB each) I can play even CODMW2 with medium graphics on a 8800 Ultra and get 40-60FPS, not to mention other older SIMs.

So yes I would suggesting getting up to 4GB as it wouldn't hurt and might give the OP quite a boost in performance. Though if your running @ 60+% system RAM usage, you might need to go higher or learn to tweak your OS to use less.

If one has a I7 system with 6GB of RAM and say a single GTX295 or ATI 5XXX card, then that should be able to handle all but the most recent games on decent of not close to max Visual performance. As for getting a second card = SLI imo its a matter of bragging rights and possibly getting that extra 5-10 FPS.

Another thing to consider, is getting an SSD, though they are still new to the market and can be quite a chunk of change, though they are faster then mechanical HDDs.