Limewire 4.9 is not compatible with OS 10.1 (LW 4.8 & earlier were.)
Your system thinks the dmg is a quicken file because it's not a complete downld file. Use Safari to download dmg's in OS X. Netscape & Explorer often don't handle dmg files properly. The file you downlded is probably smaller in size than it should be. It might only be 100-400 KB or so smaller but still, it's most likely an incomplete file.

Send me a pm if you want LW 4.8