I'm also buy a new rig after 5-6 years. The last pc i bought is when WinXP just being released, and just last month i build my latest system.
On your case unless you're rich, SLI isn't a good value investment. For now either get the G92 8800GT 512MB or GTS version (cooler and queiter); or if you willing to wait for next month, nVidia would probably releasing the D8E (dual G92 in one card), or in April we would see the true next generation card G100 (Gefore 8900).