I'd grab Borderlands since it's backwards compatible (and pretty cheap) and play it first. If you don't like it, you can always just go straight into Borderlands 2. It's a great improvement upon the original, but you might be a little lost at some parts in the story. Keep in mind, it will be EXTREMELY difficult to get into BL1 after experiencing BL2. TPS was also a fun, good game. It wasn't as good as BL2, but only because BL2 is [i]that[/i] good. It improved in some ways, and fell flat in some other ways. Don't play TPS before BL2 though, because the pay off (story wise) is much better if you play through BL2 first. All amazing games, with great stories, and great humor. One of my favorite franchises of all time. Great choice picking it up.