EZ since you say you are not a computer guy I imagine that you don't want to deal with adding an internal HD. Get a USB external. It will just plug right in.
I have this Seagate 500 Gig external
http://www.newegg.com/Product/Produc...82E16822148235
for $109.00 (i got it at a local store for 129.00) it's great.
Sure you pay a little more for an external but there is no install to deal with and you can take it with you to a friends house and plug it into his/her comp if you want to transfer files.
thats my 2 cents.