MrFun,
You don't seriously expect me to actually pay for a Corel product, now do you?
To edit tga's and sprites and stuff for CtP(2), you're best off using Photoshop or Paint Shop Pro. Since both are produced by big companies and both are rediculously expensive (at least for a college student), I personally don't feel obliged to pay for them, but I use them anyway. (Well, I hardly ever work with graphics anyway, but when I do, I use PSP).
If you do have a conscience and only want to use cheap or free utilities, download.com is the place to be. I know there's plenty of good graphics utilities out there and at least some of them can handle tga. The main problem with most (if not all) of these utilities is that they don't support alpha channels, which is what you need if you want to add shadows to sprites or some other cool special effects. For regular tga's this isn't a problem but for the sprites this can be a problem.
Darkknight,
No, it isn't free, but it's well worth the money. Don't have the money or don't want to pay? Noone's forcing you
(Ripping AoE or ToT graphics for use in CtP mods is just as illegal AFAIK, but people don't seem to have a problem with that...)