Good question: Is Linux more stable than Windows XP? I would answer that with yes and no because it depends and many variables. You could totally ef up either operating system and walk away thinking that both suck. It mostly depends on the guy sitting behind the keyboard.
I use both WinXP and several Linux distros, mainly Ubuntu and openSUSE. I don't have problems with any of those operating systems. I like to run things lean and don't like to layer them down with junk that I don't need...meaning software that I don't use. That extra junk is more of an issue with Windows I think because it's slows the computer down after awhile. All of my computers are “stable” so the Inkscape and Gimp experience doesn't feel different to me. The reason that I use Inkscape in the first place is that it's cross-platform software. Since I am stuck on a Windows XP machine at work and only use Linux at home it's nice to have my graphics software work on anything. That I am grateful for.

As far as performance gains go on Windows and Linux and Inkscape, sometimes you get them and sometimes you don't depending on your hardware. At work I have a beast for a workstation that's about as tricked out with high end hardware as one can get (I am a Design Engineer). At home I have more of a budget to mid-level machine. I never really try to measure performance between the two since they are completely different computers. However, I must say that I am not dissatisfied with either Windows or Linux. I prefer to use Linux because I think it's a better operating system but in terms of productivity, either one lends itself to getting work done. I could go on and on about the differences between the two OS's and why I prefer Linux over Windows but I think I'll cut it short. All comes down to personal preference. Use whatever OS you feel most comfortable with, whether that's Linux, Windows or Mac.
Maybe some others would like to pipe in with spec recommendations. I like to have a couple gigs of ram and at least a 128mb graphics card (I like nVidia) and a fairly newish processor. More is always better.
Inkscape does crash every now and then but this isn't really an issue for me. I save my work often when I am working on a project that's important. Just a habit. Inkscape seems to crash on either operating system. Not ever sure what causes crashes...could be a billion things.
I do have a Wacom tablet but it's a small one. It's a 4x6 USB Graphire. It probably works a little better on my Windows machine but I haven't ever had any problems with it in openSUSE and Ubuntu. Some folks had some problems with the Bamboo in Inkscape. Not sure if those issues have been fixed.
If you are interested in Linux then I would suggest giving Ubutnu a go. After you get your feet wet and learn the basics then perhaps move on and try another distro. Maybe try the new Wubi installer that comes with Ubuntu 8.04. That let's you install Ubuntu from Windows and let's you uninstall it when you no longer want it. This will give you a dual boot system and it will allow you to measure performance with the same hardware.
