Is the ASUS P5N-D LGA 775 NVIDIA nForce 750i SLI ATX Intel Motherboard worth it or should i get the ASUS P5E? I currently have a Intel C2D 6400 but am planning to upgrade to a Intel C2Q q6600 soon.

P35 chipset motherboard actually overclocks better than 750i, it just doesn't support sli. If sli is not important, get p35.

like others have said, two sli cards will be beaten by a newer graphics card in a year or so. imo its not worth it to sli, its better to get a 9800gtx or 9800gtx2 over a two 8800 gtxs.