Neywork Database Programs

My company has recently purchased a database program called CoStar ARES 2000. This program is basically a piggyback program on ACT!2000. In order to run this program, we had to upgrade all of the computers in the office (15 Dell’s) and now wy bosswants to network this database program. In order to do so, I have been advised to replace our current hub with an ethernet switch. Can anyone recommend a cost effective approach to revamping our network? Currently there are 15 users and we’re running Window’s 2000 NT on the server and trying to run Windows 2000 XP software. Any thoughts or suggestions on this would be greatly appreciated. Thanks!