have one, nice board, nice layout for the most part. the pins for the casemount mic/headphone ports are awkward but that's only me being picky. the BIOS is easy to use. the board is probably the most futureproof on the market. it comes with some pretty decent system monitoring software as well as a whole world of extra peripheral interfaces (midi, serial, 2xSATA's & power for external SATA HD use, more USB's than you'll ever need..)
there are a lot of BIOS features in there that i'm not familiar with though so it's gonna be a while before i'll be able to say how easy she is to configure for any major overclocking and the manual doesn't go to any great lengths to explain anything, so unless you already have a fair idea, it's not a lot of use. i personally have a lot to learn before i'll be able to use all the functions in the BIOS to their full potential.
haven't encountered any SLI issues yet, but i'm only running one 6600GT so far. as for the RAM, there is a list of the approved makes and models on the ASUS website. i'm running 2x 1GB kingston valueram (model no: KVR400X64C3A/1G)and it's fine although there's a bit more latency than i'd like. i should probably advise spending a little bit more on the RAM (guilty as charged you honor, i skimped on it).
the full system is the A8N-SLI deluxe MOBO, XFX 6600GT, 2GB RAM, 160GB SATA HD (7200 & 8MB), 480W Antec Neopower PSU, Thermaltake V5000A case, 19" Viewsonic TFT. only problem i have is with the GPU which is at 52C at idle and up to 76C loaded. been on to XFX about it but to no avail so i've a new heatsink on the way. prob should just have waited for an ASUS or Sparkle 6600 but the lead time was too long and i got impatient. not to change the thread but if anyone *knows* the optimal operating range for this GPU i'd be grateful to hear cus i've been able to find nothing concrete.