Whether you go with a Mac or a PC isn't much of an issue anymore. I know someone who runs Mac OSX on his PC, and I use a really nice program called "Parallels Desktop" to run Windows XP on my MacBook Pro inside Mac OSX. There are a couple issues with Windows drivers for the Mac hardware. Generally it's not a problem, but I can't reach my video card's full potential until they release it. It connects to the net just fine and runs my adobe suite beautifully, even while I'm working with my Mac publishing software. However, if you take this route, I highly recommend addition hard drive space (500gb external is what I use, USB 2.0 works great for me, but there is a firewire port), and you may want to upgrade to 4 gigs.
As far as malware goes, I use a mac antivirus, though there isn't many out there. PC is probably safer in the long run for malware, because there are Mac hackers out there, regardless what the ignorant tell you. And it's only a matter of time before more hackers target mac (and with no antivirus programs, since everyone has a false sense of security, there will be a lot of easy targets).
In the end, if you work with graphics, I recommend a mac, but if you program, or play mainstream videogames, PC might be a better choice (unless there is a mac version of the game or they come out with the correct driver).