Hello:
The Radeon xpress 200M chipset is based on the GPU core of the x300 desktop counterpart, although it is different with respect to it acting as the CPU northbridge, and memory controller also. Plus it also has power management features to help with longer battery life. This chipset is supported in furture ATi Catalyst drivers for Windows Vista, however i don't think it is directly supported by ATi's current XP Catalyst Drivers. If not, try modding them with patje's tool (Version 3) at:
http://www.driverheaven.net/patje
Have fun, good luck, take care.