Yeah im going to purchase one or 2 of them 8800gtx in a month or 2, but at the same time upgrading to ddr2 and gettn rid of the 4200 dually, nice overclocker tho still running 2.7 stable. Im going to opt for a 6700 quad core till amd's 45nms are out. Oh and 4gb of ocz xtc.
SLI 8800's are a BIG waste of money....NO cpu out can not be bottel necked by ONE of them no matter the OC.
As for upgrading your CPU...don't get a new MB to run the Core Due yet.
Save the money for 4 -6 months for native AMD 4 core if you most upgrade.
Your DFI Expext MB will handle it.
Myself I have same MB and looking at the Optron 152 in 939 pin. Best bang for the buck!