I posted this in the Song and Recording Critique section as a response to an artist there. I thought it might be useful here too. Sorry about the crosspost.
If you just need a simple multitrack/editor, Audacity is free http://audacity.sourceforge.net . It loads VST's and has it's suite of FX. If you want a multitrack that's more studio like, try Kristal http://www.kreatives.org/kristal
If you need a robust host, here are a couple of freebies that look promising.
http://lmms.sourceforge.net/home.php (Yes, it runs on Windows)
http://www.mutools.com/products.html (There's a free version)
I use Tracktion http://www.mackie.com/products/tracktion3 . Seems it's being sabotaged and abandoned by the hardware company that bought it. It's up the disastrous version "3 point is it fixed yet?" Here's a Tracktion 2 demo http://my.mackie.com/products/tracktion/demov2.asp . Here's a Tracktion 3 demo http://my.mackie.com/products/tracktion/demov3.asp . I use Tracktion 2 and find it relatively stable and not completely removed from the brilliant version 1. Tracktion is very easy to use yet allows complex maneuvers. Tracktion 2, $150.00, is more expensive than Tracktion 3, $100.00 (a clue?). Strangely, the cheapest way to get Tracktion is to buy a mixer for $80.00 http://www.audiolines.com/Pro-Audio/Mixing-Consoles-PA-Mixers/Mixing-Consoles-%28Analog%29/Mackie-402-VLZ3 It comes with Tracktion 3.
If you can find a copy, Computer Music magazine comes with a nice host/sequencer and a bunch of plugs. Each issue usually comes with samples as well.