The following items should be added to your Tortoise SVN global ignore list before importing a .Net project into a Subversion Repository.
*.suo *.user bin obj *.pdb *.cache *_svn *.svn *.suo *.user *.build-res TestResults _ReSharper*
You can add them by right-clicking in Explorer and going to TortoiseSVN / Settings. This will open the Tortoise SVN settings window and should be on the General settings window. The second section “Subversion” has a filed called “Global ignore pattern” go to the end of the list and paste in the ones above then click apply and ok.