Usually on a notebook, but depends on what/where/why at any given time:
Toshiba Tecra A1 notebook - 2.2 Ghz Win XP
Apple PowerBook G4 15" - 1 Ghz OS X Panther (BSD Unix) - cool machine!
Toshiba Tecra 8100 notebook - 800 Mhz Win 2K
Homebuilt P4 1.4 Ghz
Homebuilt P4 2.2 Ghz
In the basement in storage ("the museum"):
PII and PIII desktops (one running SCO Unix)
Powerbook 3400c
Mac IIci
Mac SE
Mac Plus
Apple IIe
C64
TRS80 Model III
Xitan S100 bus Z80 processor - CP/M Operating System
Toshiba Tecra A1 notebook - 2.2 Ghz Win XP
Apple PowerBook G4 15" - 1 Ghz OS X Panther (BSD Unix) - cool machine!
Toshiba Tecra 8100 notebook - 800 Mhz Win 2K
Homebuilt P4 1.4 Ghz
Homebuilt P4 2.2 Ghz
In the basement in storage ("the museum"):
PII and PIII desktops (one running SCO Unix)
Powerbook 3400c
Mac IIci
Mac SE
Mac Plus
Apple IIe
C64
TRS80 Model III
Xitan S100 bus Z80 processor - CP/M Operating System