Glest is no longer maintained, and I concur you should try MegaGlest or GAE instead.
What you read about Mesa is outdated. Mesa is just fine nowadays and works well for many, many players. Here's (some of) what I get when I run ./megaglest --opengl-info:
OpenGL Version: 2.1 Mesa 8.0.2
OpenGL Renderer: 2.1 Mesa 8.0.2
OpenGL Vendor: X.Org R300 Project
OpenGL Max Lights: 8
OpenGL Max Texture Size: 4096
OpenGL Max Texture Units: 8
OpenGL Modelview Stack: 32
OpenGL Projection Stack: 32
Your graphics chipset is older, but may still work. By default, ATi Radeon 9200 SE comes with only 128 MB memory, though, so this can be tricky.