Actually, there are plenty of reasons to dual boot Windows/Linux. I dual boot XP Pro and Ubuntu 8.04 on every PC I own.
1. Its not very likely that you'll get viruses or spyware on Ubuntu.
2. I use Windows for gaming and programs that I love that aren't available for Ubuntu/Linux
3. There is a ton of free software for Ubuntu/Linux that is malware free.
4. You never know when you will need Windows for some special website, program, etc.
5. Ubuntu just doesn't crash. At least, not in last few years of me using it
6. You can say, "I dual boot Windows and Linux" and computer geeks like me will think you are cool.
Also, Ubuntu is
A LOT more customizable that Windows. I can send you some pics of my desktop if you want.
Anyway if you have any more qustions, or want some free tech support for either OS, just let me know.
Chris