Laptop: Sony Vaio PCG-R505JSK, upgraded (and unfortunately maxed out) at 384MB. This is a slower laptop nowadays (mobile P3), but it works for email, web browsing, etc., and it's very lightweight.

Main home office PC: Home-built Athlon XP-M 2200+ overclocked to 2.2 GHz (making it effectively roughly an Athlon XP 3000+), 1 gig RAM, 2 x 100 gig SATA hard drives, ATI Radeon 9700Pro video card, DVD burner, etc. This is the machine I do most real work (and play ) on

Home Theater PC: Intel Pentium 4 1.6A overclocked to 2.3GHz; 512MB RAM, ATI 9600XT, 30 gig + 160 gig ATA hard drives; this machine is connected to my 50" Sony Grand Wega LCD projection TV, using a Logitech DiNovo Bluetooth wireless keyboard/mouse, and functions as a media server (all 2000+ of my CDs are stored on it as 192kbps VBR MP3's), gaming rig for games that run in widescreen (or at least custom) resolutions that the TV can display (Unreal Tournament 2004 is DAMN impressive on this TV )

The HTPC is mostly made out of spare parts that have migrated down from the office PC over the years (except for the video card and case, which were selected specifically for the task at hand)

Well, you DID ask