WMA Unprotect - is it worth doing?

I have a big collection of WMA files - about 20 gigs (they all are from Napster) and I can successfully listen to them at home. Now I bought a car mp3 player so I decided to burn my music library to MP3 disks to listen to in a car. And, of course, I cannot do it because files have Napster protection. I’ve done a quick internet search and found a lot of tools that claim to convert Napster wma to mp3. I’ve tried some of them, because if I pay for the soft to use MY purchased files - I want to know if it worth the price. I think this is what I need. wma to mp3 (drm-removal.com or whatever, ask me - will find it again) What do you think? Would you guys advise me another soft?