Multi-boot: to each his own, but if you start playing with running your own servers, it'll get kinda painful. Webservers are a dime a dozen - you probably don't care that someone else can't get to your site when you've booted the other OS. SMTP servers, however, are a bit more of a problem. If you are in the wrong OS when an email comes in, it'll bounce, and cause lots of people headaches - especially you. So, multiboot if you must, but beware of some limitations.

Virtual tools: I ran VMWare + WinXP on my 1.8GHz/1GB RAM box for years. And it's not all it's cracked up to be for heavy-duty hacking. It's fine for testing purposes, but you don't really want to be leaving a hosted system running all the time. You can run your SMTP server on the host OS, but obviously not on the hosted (virtual) OS.

Also, a virtual OS can become really, really slow. I have a 1.2GHz laptop running WinXP, and it absolutely blew my virtual WinXP box away on handling the same problems. It was an unbelievable difference. So far, on my new box, I've not yet installed any virtualisation software. I'm not sure I'm going to, either. For small (<60 seconds running time) scripts, it may be reasonable (and thus it may be reasonable for the OP), but for heavy-duty stuff that the OP may get into, be forewarned.

Update: This may sound like I'm talking about production machines. I'm not - I like to play with my SMTP server - it's both development and production at the same time. How else can I learn about this stuff without having some live server running? :-) Even the virtual machine - I have both development and production use here. I want a machine that I can both play with and actually accomplish stuff with, so I have both development and production uses. At work, however, I try to keep a larger distinction between machines. So I'm not talking about that - I think I'm in a similar boat to the OP, with at least the obvious difference that I have a clear idea in my head of how I want to develop with perl, and the OP is still discovering how s/he wants to develop with perl. All I can offer the OP is my experiences and let him/her discern how that applies to him/her ;-)