文件上传：要保存的文件名称应该是什么？

I am going to add file upload control to my ASP.NET 2.0 web page so that users can upload files. Files will be stored in the server in the folder with the name as of the user. I want to know what is the best option to name the files when saving to server. Needs to consider Security, Performance, Flexibility to handle files etc. If I miss anything, please guide meI am going to add file upload control to my ASP