The usage of O/S between Windows 2000 a

1)Can a normal PC support different kind of O/s? For example, I would like to install windows 2000 with Linux or Windows 98, Windows 2000 and Linux together?
2)For the moment, how many software outside the market can support Windows 2000? I have try a few software but Windows 2000 do not accept the installation because the software cannot accept the O/S which contains 128 bit. Please give me opinion.