I tend to use 3D Studio Max 7 (I prefer max), or Maya, but sometimes I like modelling things in Luxology Modo, just adore modelling things in Modo. If you want to have a try with modo, download the trial at luxology.com , atleast I think you can download the trial there. Anyhow, you can try out modo, easy learning curve if you follow the tutorials on the luxology site, and you can do sculpting, paint bump maps and texturing in the program, after you do the whole UV unwrapping.
But if you want to skip all of that, just model something simple in XSI, get the mapping right, and just use any art program that you got handy for texturing. The program that is mostly used for texturing however, and the one I always use, is good old Photoshop.
There is a whole bunch of tutorials available on the net, just search for them. However, you can always drop in at a 3D forum, like cgtalk.com, and just scroll down until you get to the XSI area, pretty sure you'll find a whole thread dedicated to tutorials, from beginners to novices to experts.
Hope my rambling helps
edit: here's an old pic of something I made for a game art competition. Had to make a character under 5000 triangles: http://www.furaffinity.net/view/1712089/