Simply rename Yourfile.csv as Yourfile.txt. Then open excel (no file opened), start open file dialog, set file type as *.txt, and open the file. You are given options like delimiter, field types, etc. Set for every column right field type, and open file - data will not be mangled then.

Maybe same options are given when you open csv file from Excel instead double-clicking it too, but I don't remember can you or not, and I don't have Excel available currently.