MacBook Pro: swollen battery, warped case--worth replacing battery?

Yes--should have taken it in sooner. Actually, the track pad has been acting weird for a long time before obvious warping. It tracked ok but the clicking is very inconsistent with some dead spots. As mentioned, it's my wife's computer and she never said anything about it. Only when I used it once did I notice the problem with the track pad. I chalked it up to typical wear and tear, never thought about the battery until I did some reading. Only now, months later (!) the lid stopped closing. Then I finally figured out things were really bad. My fault on that.

In any case, the big question is whether it's worth it to replace the battery and try to milk another year or two out of it. I sense that the better bet may just getting a new one.

Yep, the uncertainty is the issue. It's mainly my wife's computer. She tells me that the apps basically work well (she's a light user, and when I purchased the MacBook, I maxed out the RAM so she has more than enough for web surfing, email, etc). However, the power system is messed up. It gets "confused" sometimes when opened, showing a certain amount of batter y power then turning black and shutting down. You need to plug it in and reboot, etc. But this is surely all tied to the battery. The screen is in decent shape, with a small "dead spot" where the pixels seem to be burned out.