No one is safe from worms in any windows operating system.
Best thing to do is to practice some common rules.
1. Don't open attachments that you don't reconize or didn't ask for.
2. Don't use the Outlook preview pane that allows scripts to be ran in the preview pane.
3. Use a firewall.
Freeware version of ZoneAlarm or
Sygate Personal Firewall are just a couple of them that are advailable out there.
4. Use an Antivirus program.
AVG Anti-Virus
Or regular use some online scanners that are free like:
HouseCall or
Symantec Online Security and AV Scanner
If you do use an Antivirus Program locally make sure you update your definitions regularly.
5. Keep windows updated if possible.
That is about it.