Well, I don't think that Windows98 sucks for home use - IMHO it is in fact more secure than XP, due to the reasons that Apocalypse cited. However you must install the patches from MS (windowsupdate.com) , together with a firewall & an AV scanner.
For professional use WindowsNT, Windows2k, and some flavours of *nix are more secure - Linux is OK I guess, but it's not what I would choose.