Uh... I would recommend against going to the 2.5 branch unless you know that you have to in order to make your hardware work. Kernels with an odd number for the minor version number (2.1, 2.3, 2.5, etc) are in the development tree, i.e. that's where are the new stuff gets tested, so they can be unstable and generally unfriendly to a newbie.
What you probably want is 2.4.18 (maybe it's 2.4.19 by now) which is the latest stable version.