Jhet - 1:46 pm on May 25, 2011 (gmt 0)
I'm pretty sure it wasn't a browser virus. It was only showing spammy code on the Google cache of my site and nowhere else.
If it happens again I'll definitely look for eval/base64. I think what happened was that the hosting company caught the hacked site before I did and they fixed it without telling me. By time I seen it only Google's cache still had what the hackers did to the site in it.
I went to webmaster tools and had the cached pages removed. Several of them have been re-cached and no longer have all the spam keywords in it.
Thank you everyone for the help and advice!