The UD3P CAN NOT SLI. CROSSFIRE ONLY, unfortunately. If you'd like a board that does SLI and overclocks well, you could always check out the
EVGA 750i SLI (FTW), or if you are/become ambitious, there's also the
780i SLI which will let you Tri-SLI...
I wouldn't bother adding more RAM and then trying to OC it, you might as well get a DDR2-800/1000/1066 since DDR2 is suddenly dirt cheap.
Here Are Some Good DDR2-
1000 Or Higher Kits For Your Purusal, If You Wish.
Just as well, I would reccomend you get a new Video card, cos you might want one to go with your new system, like a burger and fries, or cheese and wine, or beer and nachos :D
There's the
XFX 4830 - $150, falls in between a 3870 and 4850, significantly better than the 8800/9800GT (8800/9800 are exact same card, but one has Tri-SLI), or if you really like Nvidia you can go with the
9800GT - $130 which is still a very decent card.
A step up from those is the
4850 - $190, gets you significantly more frames than 4830 for $20 more. Then, there's the Nvidia equivalents, the
9800GTX+ - $210, which is actually a bit better than the 4850, but once again for $20 more. This card used to be the 9800GTX but NV did a 55nm refresh and the results were significant. Another step higher, we get the
HIS 4870 - $240, which once again has significantly more frames than the 4850 or 9800GTX+. The NV equivalent is the
GTX260 C216, which is far better than the 4870, but costs over $300.... :D