Limewire has been one of the most popular P2P programs to date. It never achieved the same level of popularity as Kazaa but once Kazaa went down as one of the top P2P software programs Limewire took over and is still going from strength to strength. The only problem is you have to connect up and share your files online. The default setting on Limewire actually shares folders on your PC that I am sure you wouldn’t want to share. So you have to manually check these settings yourself.
I remember watching this article on the news talking about Limewire’s default settings and how users without their knowledge were sharing more than they cared to share.
Rapidshare is completely different. Someone uploads a file to Rapidshare and Rapidshare hosts these files and gives a link to the person who’s uploaded a file. Now the uploader can send his/her Rapidshare link to his friend or whoever he chooses. This saves them uploading files to multiple people.
Limewire works differently. You share your files in order to download files, which i guess its only fair but you must change the sharing folder from default so you’re not sharing important documents that billions of people could get access to.
Limewire has access to tons more files, movies, games, and music. You name it, it’s on it. There are also no file size restrictions like Rapidshare suffers from. File size has no boundaries on Limewire but you are also relying on the amount of users that are sharing the file as well, the more users sharing a file on Limewire the faster the download.
Rapidshare loses this battle when it comes to file size as their uploads are restricted to 100mb but it doesnt rely on users having to upload the file as all files are hosted on Rapidshare. The benefit of this is that no one is downloading anything from you and you can download what you want depending on your Rapidshare account.
My honest opinion is both are brilliant for what they do. Limewire wins hands down as its got millions of people sharing files and Rapidshare still requires a good search engine to find these Rapidshare links plus the limitation of file sizes limits it slightly. But Limewire is only better if you know how to operate it, you know which files are complete BS to the ones that are genuine ( I will be doing a Limewire video tutorial on how to manage Limewire more effectively).
Rapidshare is alot safer to use than Limewire because you are not actually sharing any files, you are simply downloading. Limewire is giving access to thousands of people searching through your folders and I am sure there are RIAA and some government bodies are also taking a peek at what your computer is sharing to the Limewire community! 
This is an even fight. If you want more files, bigger size downloads, movies etc then Limewire is the clear winner of the two, but if you’re looking for a safer environment using a Rapidshare search engine to find files on Rapidshare is safer.
