It's recommended that you re-rip music directly from your CD's in Ogg Vorbis or mp3 format, rather than converting from WMA or AC3. Use a USB card reader to copy your ogg or mp3 files from your PC to a Memory Stick for your TJ35.
The higher the bit-rate, the higher the fidelity of the compressed file, but the larger the music file; a bit-rate of 128 is a middling compromise. Try some different ones and see if you can hear the difference. If you can't, use the lower bit-rate; then you can store more music per Memory Stick.