I found this program that you can use to clear most recently used files in VS 2005.
http://www.csharper.net/blog/mru_cleaner_v1_0_0_5___now_serving_your_file_cleaning_needs.aspx
http://www.csharper.net/blog/mru_cleaner_v1_0_0_5___now_serving_your_file_cleaning_needs.aspx