I'm confused by the 3GB RAM, 500GB HDD, and the lack of Blu-Ray ability.
For a custom, high end gaming unit (it has an i7 in it) it should have no less than 6GB DDR3, 1TB HDD, and should have a Blu-Ray player (if not a burner).
But as someone else mentioned, don't look a gift horse in the mouth. I've signed up anyhow, as it'd still be a great machine. But it could use some upgraded options.
Also, keep in mind folks the reason companies do contests like this is to collect email addresses, phone numbers, and mailing addresses for prospective customers. Thereby, by signing up you're giving them permission to start (e)mailing you stuff.