I haven't tried it personally, but if you are looking for assistance with ASP.NET MVC Validation, there is an ASP.NET MVC Validator Toolkit on CodePlex.
Per the ASP.NET MVC Validator Toolkit Project:
"The Validator Toolkit provides a set of validators for the new ASP.NET MVC framework to validate HTML forms on the client and server-side using validation sets. By defining a validation set, e.g. a LoginValidationSet class, the toolkit will generate code, in conjunction with the JavaScript library jQuery, to validate on the client-side and will use the same set of rules to validate on the server-side."
You can download the ASP.NET MVC Validator Toolkit here.
ASP.NET MVC Validation Tutorials: