Is it wortwhile to go from 1 to 2 gigs of RAM?

I have an ASUS A8Ne MB with a 939 socket. The cpu is an Opteron 170 and the video card is a GeForce7900GS with 256megs. I currently have two of the four memory slots occuppied with two sticks of Crucial Gold CAS2 400Mhz PC3200, 512megs each.
I've been reading some of the forums where the overclockers and real fanatics reside. The concensus is that going from 1 to 2 gigs really improves the performance. Also, the majority seem to feel that the only acceptable way to do this on a DDR board is to pull the two 512 sticks and place two 1gig sticks in. Otherwise, by having four 512 sticks, the timing goes from T1 to T2. I have no clear understanding of what that means. Is it a real degrading of performance, or just an inconsequential drop in numbers on some benchmark tool?
I'm looking to go to 2gigs, and the cost is $181 for two 1 gig sticks of Kingston Hyperex CAS2 from Newegg vs two 512meg sticks for ~$85 from Frye's. Same brand, latency, etc.
Which way would you go? I realize that if I bought two 1 gig sticks, I could sell my two 512s.
Playing games like Half Life2, Quake4, etc. is it really necessary to go from 1 to 2gigs, or is the extra ram just going along for the ride?
Thanks.

 

...standby...tracking down "real fanatic "....okay, fanatic located...

Skaler, going from 1GB to 2GB is a good idea if you play current games and intend to continue playing new games as they are released. Each new game that comes out is more of a memory pig than the last. There are games that came out in 2006 that indeed benefit from 2GB. Ghost Recon Advanced Warfighter is one example. But I wouldn't consider it critical. But based on your rig's specs, it would probably be a logical next upgrade.

Will it result in noticeable performance improvement? I wouldn't say that it would be really noticeable but it will help smooth things out a bit.

Regarding the 2-stick vs. 4-stick debate...even if you go with two 1GB sticks, there's no guarantee that you'll be able to run stable with a memory Command Rate of 1T. Far from it. I had two 1GB sticks with a Venice 3500+ and I could not run at 1T at all. When I swapped out that cpu for a San Diego 4000+, 1T was no problem.

What did I get with a command rate of 1T? My RAM throughput (measured by Memtest86) was boosted by 300Mb/sec. Like from 2GB/sec to 2.3Gb/sec - or something like that. My 3DMark05 score went from ~10,300 to ~10,400. Whooopppeee! A command rate of 1T used to lead to instability on Athlon XP systems but I'm running it on an Athlon 64 system with no trouble.

Most likely, if I were you I'd probably go with buying two more 512MB sticks to reach 2GB instead of scrapping the two you already have and going with two 1GB sticks. The benefit of 1T is not as tangible as you would hope. But if you do do that, try to buy the EXACT same model of RAM. As such, you should be able to enjoy the benefit of dual channel even with 4 sticks (depending on your mainboard) - but even that isn't guaranteed without "matched" pairs.