If you don't like Windows, I'd strongly recommend getting an Apple Mac, Linux is a step backwards not forwards. If you want something you can tinker with under the hood, stick with the American original, Unix, not foreign clones like Linux. Try Sun Solaris or PC-BSD, here's all you need to try them out, so long as you have 512Mb total system RAM:
http://www.vmware.com/download/player/
http://www.vmware.com/vmtn/appliances/directory/420
http://www.vmware.com/vmtn/appliances/directory/71
The only reason why that I'm leaning towards Linux is that it can support Java (I'm a Java Developer) and I heard that Windows Vista can't support Java...