Intel Pentium Dual Core E2180 2ghz  CPU (O.C @ 2.8ghz)
2GHZ Corsair XMS2 Ram
2 x 8800GTS G92 in SLi
 
Thing is, I've decided, after seeing benchmarks.. that 2 8800GTS cards in SLi mode are the best option for me... and have just paid for my first card but Im worrying that the CPU will be holding it back. Will this be the case.
 
Only paid £160 for my Gigabyte 8800GTS...... Bargain! Considering its priced at £200 elsewhere.

OHH yes you will, if what you say is right. A Pentium D? or a Core 2 duo? the E2180 sounds like a Core 2 Duo. If it is then you should be ok.
 
But if its a pentium. no way. Why did you get 2x 8800GTS? that seems like a bit overkill.

I went for the 8800GTS because of the price... not much more than a GT but has the edge over the GX2 when SLi'd... and Im after the best performance I can get without spending a fortune.  
 
Yeah its a Core2 but Intel badge them up as Pentium Dual Cores...

Couple of things. Why do they do that name one as a Dual core and another as a Core 2 duo ? is it to do with the stepping or something ?
There must be a reason, It dosent make sence if they are identical as they need two differant lots of packaging etc.
 The second is are you running a high res to want to sli GTS, if you dont mind me asking. Or do you just want all the whistles and bells to work.
 Mactronix

 
one has a brutal amount of cache disabled (the pentium dual core). it's still a great processor, if you can get it over 3.2Ghz

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E6300@3.2ghz 1.32v  |  Gigabyte P35-DS3R 1.0
4x1GB C5@900Mhz    |  8800GT

to the OP.. if you have the money for 2x8800gts, what stopped you from getting a E6xxx or E4xxx CPU? just wondering..

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E6300@3.2ghz 1.32v  |  Gigabyte P35-DS3R 1.0
4x1GB C5@900Mhz    |  8800GT

Because I got this system extremely cheaply... I swapped a 7950GT (cost me £20), an ASUS T3 Barebone case, E2160 CPU and 250GB Hard Drive for a media centre case, nForce 650i SLI mobo, E2180 CPU, 80GB HDD and 2 x 6800GT's...  
 
Im selling the 6800's... and will eventually upgrade the CPU but it'll do for now.
 
I'll be running at 1680 x 1050 resolution... mainly for Crysis and other modern FP shooters.

 
And my other machine is E8400, X38 mobo, 4GB 1066mhz Ram ... but I dont like how Crossfire scales in Crysis, whereas SLi is much better.  
 
Once ATi fetch out a worthwhile GPU... I'll stick to my new and cheaply acquired SLi rig.

@OP: Make sure you have a good PSU before doing SLI. Yes, a E2180 @3Ghz, should not be much of a bottleneck at high resolutions.

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E2180 @3.2Ghz + P35DS3L +8400GS (700/475 OC)  

I've got a 300Watt ASUS PSU for the PC... and a dedicated 250W SLi Power Supply to feed current to the 8800GTS's...