A good virus scanner like norton along with good computer hygene should hold you over until Vista. Just be careful because it's all the "sekret" viruses that get the bad press but most adware/malware comes from content users willing download from Internet Explorer. Know all that "totally free" porn that you simply have to download their "tools" to view? Well, their "tools" are typically adware/spyware stuff
Macs don't have as many of these problems because there are less mac desktops hence a smaller target for virus writers. If you really want to be safe, download Linux and use that