Can Free Realms damage your computer

Free Realms is a children's community and entertainment site, with enhanced privacy and data protection policies to cater to its younger target users. The site requires (but cannot reasonably enforce) parental permission according to their terms.

It falls under the umbrella of Sony Online, so the pubic image of a large corporation hinges upon the safety and integrity of the experience they provide. Logically therefore, they would not be prudent if they employed malicious software in their service.

Ultimately, as with any online service, you can only decide whether you personally trust any warranties or assertions they make. The same safe-practices still apply regardless of the reputation of the service provider.