Hello Pradaboy,
if you can't make it with winrar's maximum compression, i'm afraid no other archiver can make it better. You may try the following:
1. Get a 800 mb CD instead of 700 mb one
2. Try to overburn your existing CD (Nero allows it)
3. Compress your ISO into multivolume archive and record it to two CDs
4. Write that ISO file as an image to a CD.
Hope this helps