Are you hoping to get higher quality out of your files by doing this?
You won't. You'll actually audibly
decrease the quality of your files, as transcoding or re-encoding between lossy formats always does.
Do yourself a favour and re-rip your files from the original CDs, using
EAC and
OggEnc. (It's a little complicated to set up for the first time, just post again if you need help.)
If you still want to transcode (again, I'd
strongly recommend not doing so), you could use
xcLAME.
All of those programs are free. You'll find that most commercial software in this category is absolute crap and not worth spending a Euro on (except for programs like Cooledit of course).
CU
Dominic