There's a d20 version of Shadowrun?  *shudders*

I don't mind class based role playing games but I'm not particularly fond of them for modern or future era games.  They just don't seem to capture the ability of a modern person to just go out and learn something.  If you do end up playing Shadowrun make sure your character carries an old school revolver as back up!  It really sucks when a rival decker puts your high tech sliver gun into self-diagnostic mode!

Rifts is also great.  The system sucks and nearly everbody creates their own house rules as a result but it's a great melting pot of insanity.