My Gapkiller program has a fairly easy-to-use splitting feature, the only hard part is deciding where to put the track breaks. Note, if you use Gapkiller remember that the file must have only ID3v1 tags on it (you can re-add V2 tags after you're done messing with the files), and if you split VBR files you need to fix up the headers on the resulting split files (for instance, with MP3 Tag Studio).