Try this.
http://www.parallels.com/
There's a free Beta so you've got nothing to lose.
No rebooting.
It's VM, (virtual machine) which is not the same as emulation.
Emulation like the old Virtual PC product required the PowerPC processor to emulate an Intel chip which is what made it suck but it was the only option.
You can have multiple Virtual Machines running simultaneously.
On a scale of 1-10, Emulation is a 1, Native (dual boot) is a 10, a VM is around an 8-9.
My webmaster is running it on his new 15 inch MacBook and loves it. He's got Windows 2000, XP and a Linux distro set up.
I'm just waiting for the 17 inch MacBook.
Scott