Sorry, but I can't suggest you software I've never used. You may try CDFS.VXD if you have Win9x. It will allow you to copy CD tracks as .wav files.

You may find free open source CD rippers at SourceForge
http://sourceforge.net/search/?type_...sole+Windo ws

And the list of CD Ripping projects can be found at sourceforge.net:
http://sourceforge.net/softwaremap/t...p?form_cat=118

p.s. As for slow computer, you may change the process priority easil. You shouldn't notice your computer slowing down after that when doing "insignificant" tasks.