Way too many.
1 Windows desktop that I use for gaming. (AMD Phenom 2.5Ghz Quad-Core w/ 4GB RAM)
1 "Hackintosh" (homebuilt Mac) for when I want to use MacOS X. (Intel Pentium 1.8Ghz Dual Core w/ 2GB RAM)
1 Linux desktop that i use for my normal web browsing and computer usage (AMD Athlon 2.1Ghz Dual Core w/ 2GB RAM)
1 Testing machine that I use for playing around with whatever catches my fancy - it's currently has HaikuOS installed (AMD Sempron 2.0Ghz w/ 1GB RAM)
1 Laptop hooked up to the TV for transferring movies to it (AMD Athlon 1.0Ghz w/ 512MB RAM)
1 Laptop to actually take places and use (AMD Sempron Mobile 2.0Ghz w/ 2GB RAM)
And 1 older PowerMac G4 (Dual 550Mhz PowerPC's with 768MB of RAM)
Plus enough scattered parts to get probably 3-4 more running from the pieces
.
This isn't counting my router which is running a custom firmware or my D-Link NAS file server, both of which are running some flavor of Linux and can run small programs like Bittorrent clients or iTunes servers as needed.
Yeah, I'm a computer nerd
.