http://www.amazon.com/Seagate-Backup-Desktop-External-STCA4000100/dp/B00829THLE/ref=sr_1_2?ie=UTF8&qid=1364044697&sr=8-2&keywords=external+terabyte+hard+drive

worth it

do a multiple-drive setup if you have a desktop. also in the interim clear out old downloads/temporary files etc to save space until you get the new drive

Easy for steam games. Just drag the steam folder.

I think steam beta allows you to just install games to a different drive.

http://www.newegg.com/Product/Product.aspx?Item=N82E16820147194

pretty sure the OP didnt state that he had infinite cash

http://www.amazon.com/dp/B005T3GRNW/

I've used a 1tb internal and 1tb external setup for awhile now and I have to say I'd much rather have 2 internals. The only reason I bought the external drive was when I was traveling back and forth between college and my home town. If you're not planning on traveling I'd say just go with 2 internals as it is a cleaner setup.

Adding a second drive would be the simplest/quickest solution. You can then cut/paste your steam folder to the new drive. After that you would have to create new shortcuts to steam, but no big deal. Other games would probably need to be reinstalled. Create music/video libraries on the new drive and move those files over if you need to.

Easiest solution that I used was to download a tool like Acronis True Image, buy a new hard drive http://www.newegg.com/Product/Product.aspx?Item=N82E16822236008&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&cm_sp=&AID=10446076&PID=3938566&SID= or http://us.ncix.com/products/?usaffiliateid=1000031504&sku=65701&vpn=ST1000DM003&manufacture=Seagate&promoid=1293 or http://www.outletpc.com/df5548.html?utm_source=df5548&utm_medium=shopping%2Bengine&utm_campaign=pcpartpicker and just install it and copy over the data using the second drive you purchased earlier as extra space for music/downloads/etc

http://www.ncix.ca/products/?sku=77212&vpn=MZ-7TD500BW&manufacture=Samsung%20Memory%20%26%20Storage&promoid=1293

Save about 150 dollars.