I have Guitar Tracks Pro, and while it is a pretty good program for a hundred bucks, it has some "issues", particularly in the area of soundcard driver compatibility.
GTPro uses MME drivers, while it can get by with WDM drivers, it will access them in MME mode, what this means for most people is that although cakewalk tout GTPro's ability to work at 24 bit, most WDM drivers when accessed as MME will only support 16 bit performance.
If you are running win2000/XP your soundcard most likely uses WDM drivers.
GTPro allows you to use up to 16 real-time effects at once, and will only allow a maximum of 3 effects per track or aux, and only 2 on a main bus, this is actually a very limiting factor, especialy concerning the main bus.
I use Sonar 2.2 XL as my main setup, and now that cakewalk have seriously updated Home Studio 2004 to be very much like Sonar "lite" I will probably be getting that to use on my laptop.
The XL version of HS2004 has all the effects in GTPro except for the Revalver SE amp sim(which I never use anyway), and will allow up to 24 real-time effects at once, without the track/bus limitations, this is pretty important for me. It can use MME, WDM, and ASIO drivers, and should be able to give you "no bullshit" 24 bit recording under win2000/XP. And like Sonar it can be setup with up to 16 aux busses instead of GTPro's 2, I usually run 4 aux busses.
After taking a good look at HS2004 XL, it is IMO well worth the extra money when compared to GTPro.
I dunno much, I heard alot of good thing about GT Pro, but the backward is, it's not that MIDI friendly. It's good if you just do audio (guitar) work IMHO.
