browser/safari hijacked

Does anybody know where I can get some free spyware, or even a firewall?

It appears that my browser has been compromised. It keeps going to wsearch.net and I cannot find where the trojan or whatever is myself. I've removed the cookies and cleared the cache, however its still there.

Thanks in advance for your help.

P.s., i jus bougt my macbook and i'm not certain if its 10.5.

Gracias.

Clear cache in Library as described here:-

really clear safari cache [Archive] - The macosxhints Forums