I'm planning to buy a new PC [ CPU: Intel Q9550 , MEM: 2x2Gb 1066MHz DDR2, GPU: GTX260 or 275 ]. Its a little hard to find out which mobo is better : P5Q , P5E , P5N-T Deluxe.
I'm going to use this PC 8 hours ahead without standby/shutdown for heavy works [rendering, gaming]. SLI support is a plus because I'm going to use a FullHD 22" monitor. [ I don't want to use ATI cards at all ]
I'm planning to buy the P5Q. Currently I'm not planning to OC the PC or use special cooling systems [perhaps will do it later].
P5N-T Deluxe looks great regards to its 3way SLI support but it looks too buggy and crashes most of the time [ depending on their support forum and other forums ].
I have a P5N-T running the second newest BIOS 1301 I think - think 1401 is the latest.
Anyway, I have pretty much the same as what you're looking to build - Q9550 and 4gb Dominators (4x1gb). I've found the board is stable and runs well on the 1301. No issues with Vista 64.
Did have an issue on older BIOS with XP and SATA optical drives which would cause GTLDR errors - fixed this with the 790i SATA driver, but as I say no issues with latest drivers/BIOS/Vista64.
However, I would only get the P5N-T if you will definitely use SLI in the future, and moderate-high overclocking won't be an issue in the future. The 780i is not good at clocking quads - I can only reliably get 400 FSB (3.4Ghz) with reasonable northbridge volts, whereas I could get 475+ with a dual. The Intels are stonger chipsets IMO, so only go with the P5N-T if you will use its unique features - I.e Sli.