Well, if you wipe the entire drive including the operating system...it won't run at all lol. You'll get past POST and get an error message.
To completely wipe the drive there are several programs you can use. I like "WDCLEAR" because it's simple and free to download.
If you want to keep the operating systme on there and just get rid of all the data...well I wouldn't suggest that at all really if you are donating it. Wipe it entirely.