Why not use the asp.net validators? Could you explain why the inbuilt validation controls don't meet up with what you want?
If it is a case where you need to know more about how to implement them, then these articles may provide you with the information you require to get the validators to function the way you want them to.
Exploring ASP.NET Validators[
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Customize Validation Summary[
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ASP.NET Validators Unclouded[
^](This one is really old, but may still have some useful information)