@benseven hit it on the head. Windows cannot run a reliable, virtual version of OS X and iLife is not Windows software.
There’s a discussion about this, with links and more information, on Metafilter.
You could always get a PC capable of running a modified version of Mac OS X, if you’re not opposed to pirateering. I have an MSI wind that boots OS X like a dream. If you want a dirt cheap option, you could always roll your own Mac for 150–200 bucks. Garageband, maybe the most intensive iLife application, runs sweetly on my MSI Wind.