I have the free version of LimeWire and am considering purchasing the Pro-Version. What are the differences? and particularly how much faster is downloading with the Pro Version? The Free Version is very slow for me.

Pro connects to 5 ultrappers compared to basic's 3, so the potential's there for better search results. People who are looking for rarer files say that there's a real difference, if you're looking for popular files then you may not see any difference.

Pro will let you connect to a few extra hosts for download...14 if you have a T3 connection. So there's the potential for extra speed. But if you have a really slow connection, it's not going to make much difference at all. Or if your ISP is managing your bandwidth when you use p2p, having Pro isn't going to change that.

Pro entitles you to either 6 months or a year's worth of free upgrades & email support, depending on whether you buy Pro for a year or 6 months.

Who is your ISP?
Download a file from here & see what speed you get.
Magnetmix

Have a look through this thread for info about maximising LW's performance.
A few things to consider while configuring Limewire for optimal performance...