Uschie,
In my opinion, Pro is the better of the two OSes, however, I wouldn't pay for the upgrade to pro, unless I really needed it. Take a look at the features in the article that blackwar pointed you to, and determine for yourself which is the best for your computing experience. I have always used pro editions since windows 2000, and have been entirely satisfied. I think however, if you don't need the extra features offered by the professional version, then don't upgrade... why waste your money...
BB