I'm not in any way plugging/advertising for Sager, but a NP9260 with SLI 7950s, 2.13 C2D, 1x 1GB RAM, 1680x1050 LCD, Vista Ultimate, 80 GB 5400 HD, 4965 AGN, Bluetooth and ExpressCard Remote costs less than $3000. You can upgrade the LCD, get 4 GB Ram and a 200 GB 7200 HD without pushing much past $3500. And it has LGA 775, so upgrading the CPU isn't nearly as pricey; room for RAID 0, 1 or 5 also.
You can also get the EUROCOM D900C, a similar and slightly more pricey lappie, with its option for 95W quad-core C2Ds.
To be honest, though, $3000 would build one heck of a desktop.