Many here will advise you against installing any anti-virus software, but it is, of course, your choice.
If you've run the uninstaller but bits are left behind you could download the free EasyFind which is brilliant at finding all kinds of detritus:
Regarding anti-virus - you may find Thomas A Reed's Malware guide useful reading:
P.S. Whatever you do, don't install MacKeeper, based on reports on this forum and elsewhere.