The Waves Ltd. GTR Solo is guitar amp and effects modeling software that Waves has made free for a year! The software can be downloaded from Waves' website and with a short registration process. It shouldn't take too long and is available for all DAW's that I'm aware of. The software comes with a series of modeled amplifiers as well as stomp boxes for effects of all kinds. It splits it up into separate plug-ins for your amplifiers and effects. There is also a tuner for helpful inside the box guitar tuning. The plug-ins aren't hard to use and there's definitely a lot that can be done with them. I've never checked out the manual for GTR Solo but there is one available for it that I'm sure is in depth enough for users on all levels.
I'm running the Waves Ltd. GTR Solo software in Pro Tools 9 on my system at home. My computer is a Mac Book Pro that has a 2.2 Ghz Intel Core 2 Duo processor and 4 GB of RAM, while I'm running Pro Tools 9 with a Digi 002R audio interface (or standalone as is possible with PT 9). It doesn't take up too much processing power from what I can tell and from how I've been using it on my system. Of course it will vary depending on the system you're running it on, but in general I think users will be able to run it without problems.
It's really awesome that Waves is letting everyone get GTR Solo free for a year, and of course I'd highly recommend taking advantage of this. It's a pretty awesome tool for in the box guitar modeling and for getting effects of all kinds. It's never going to sound like the real thing, but considering how many different options there are here between the amp modeling, cabinets, effects, and utilities, it's great that everything sounds great. You don't need to take my word for it, just check it out for yourself today and see what's it's all about...