Download some of the good free choices for antivirus / anti-other-malware and run one of them. If you want to be really thorough, uninstall that one and do the same with another. Here's an older thread where a number of members have weighed in: http://www.tomshardware.com/forum/30745-63-computer-anti-virus-spyware-programs-free
I personally use Norton's Internet Security, which is a paid product.
Is there something in the computer's behavior that makes you suspect spyware? Do you have any security software installed now?