I'd like to get a Mac emulator up and running on a partitioned hard drive and I was wondering if anyone can reccommend an up to date emulator.

My system is a pentium 4 3.2ghz processor, 1gb of ram, 128mb Nvidia Geforce FX graphics card. I assume its capable of running an emulator reasonably well. Would I also need to install a mac operating system to get the emulator up and running?

Any assistance on this subject would be appreciated.