Luisfius: Weekend Deal at Steam is Borderlands with 75% off at everything. 7.5 bucks for GOTY edition, which is the game and all the DLC. Very worth it.
http://store.steampowered.com/app/8980/
PincushionMan: The GOTY page says it uses SecuROM - is that the dreaded 3 install limit that I've heard so much about?
Also, if you have the base game, you can buy a DLC 4-pack for ($7.50 - cost of GOTY), but one or more of those has SecuROM also.
I'm not sure. I know the original boxed release had pretty much no copy protection at all, but the DLCs did have 3 install limits. In the GOTY, I'm not sure if its the DLCs or the whole package with it.