My wife and I both bought a set of the Logitech Z-2300 and they are AWESOME.  I've did a lot of research to find out what a really good but relatively cheap set of speaker were and these rose to the top.  I am most definitely not disappointed with them in the least.  Also, from what research I've done, you're much better off with a nice pair of 2.1 (for the price we're talkin) than a crappy set of 5.1.  Plus, if you're like me, all 5 speakers are just gonna sit right in front of you anyway...
Check 
Pricegrabber.  They usually have some good deals.  However, I know the price at Dell Small Business will look tempting because it's so low...DO NOT order them from Dell Small Business.  They will jerk you around for a month and a half and tell you that they're "sorry your oder has been delayed but we are trying our best to get the items in stock" before they flat out cancel your order.  Newegg, PCNation, Zipzoomfly are all good.  Got mine from PCNation (after the Dell Small Business fiasco) with free Fedex shipping and got them in 3 days.
One concern is that the subwoofer is a little large (which isn't a problem for me, but it might be for some people).  If you plan on putting it under your desk, I would check the specs on the sub to make sure it'll fit where you want it.  Don't get me wrong though, this baby more than makes up for it's size with the quality of sound and bass it produces.  Buy them now, you won't be disappointed.