I have been using Visual Studios '05 for some years, but its too old to open the ServeUO.sln

If I have get a newer version, what would the lowereds compatible version be to recommend? I can get '08 cheaper.. would that be allright, or do I really need the 2010 or even the newest 2012 version to keep up with the project?

Im sure I can use my '05 if I created a new project, but Id rather use the project already setup.

2013 is out now. Although we currently use 2012 for ServUO. You can get the express version of 2012 free directly from Microsoft.