2 problems
 

First problem being that today for the first time ever when I went to use limewire, something happened. something popped up saying that "One or more neccesary files appears to be invalid. This is generally caused by a corrupted instalation. Please try to downloading and instaling LimeWire again. If the problem persists, please visit www.limewire.com and click the "Support" link.
Thank you"
Thats the message and i did re-download it and this still popped up. I've had limey for 1/2 a year now and nothings ever happened.

As well, my second question being, how do I make it so if I were to delete limewire i could keep all my music, other then burning all the songs I got on to a dvd disc and then putting them back on my computer? Thanks in advanced for the help, sorry for being a noob.

For the corrupted install error:

First, update your Java using the offline JRE installer (point 1 below). Remove your current Java version before you install the new one;)
Fixes for LimeWire
Delete LW's preferences folder when LW's closed (that's points 2 & 3 above).
If that doesn't help, reinstall LW using the offline installer (not the recommended one).
http://www.limewire.com/english/content/download.shtml


Where's your saved folder? In LW tools > options > saving will show you the location. The default is C:\Documents and Settings\your name\Shared
If that's your location then it's fine, you should be able to uninstall LW & your files are still saved there on your computer. If you've moved the saved folder to another location, make sure it's not within any of the LW files that will be deleted when you uninstall:D