quick and dirty backup

I have a user taking up a lot of space on the server, so i had him move all the old stuff he doesn’t need to a separate folder. now i have 30GB to archive and it is just a hodge podge mess. Any suggestions as to what i should use? 10 DVD’s? or an external hard drive? We would like to have two copies, so it would be twenty DVD’s or two external hard drives. It is a windows domain network with W2k3 server and WinXP desktops. We have two Buffalo terastation NAS.