Yep, lots of emulators for linux. Here are the ones I use:
Mupen64 for N64 games.
Fceu for NES games
ZSNES for SNES games.
VisualBoyAdvance (with Gnome Boy Advance GUI) for GBA games.
I don't know about Linspire but with Debian Etch you can apt-get all of these (except for Mupen64).