This is probably the most predictable post ever, but, since you mentioned you want to use this for training in the IT field, I cant resist...

Have you considered an Intel Mac? The reason I mention this is that you get 3 platforms in one this way, including OS X, Unix, and Windows. You could also put some flavor of Linux on it, and there's X11 (I know nothing about it though).

Windows IT guys are a dime a dozen, but if you have knowledge of other platforms in addition to Windows, you will be far more marketable -- plus you'll have a significantly richer knowledge base.

As an independent software consultant, my fiancé keeps a lab with an assortment of machines. This allows him to keep up his knowledge on all of these platforms and also allows him to troubleshoot issues on his own systems instead of his clients'. He works with IBM products, and the assortment in his lab happens to be more extensive than what IBM keeps on-site. All of this makes him more marketable to the client. They often have legacy systems of many sizes, shapes and colors. When others might say, "I don't know anything about that," he can say, "yes, I'm familiar with it. In fact, I have one in my lab." That really impresses them. Similarly, if you're asked about your experience with Unix in an interview, you can say that, in addition to your various Microsoft certifications, your primary machine runs BSD (Unix), and you are quite familiar with it.

Anyway, just something to consider.