I should have been a little more specific - it's not one big thing that's wrong with the car today. It's just an old, dated car. It's got some things that are small, some not so small (trans is wearing, clutch is on the downslope of it's life)
I realize that one of the big factors is examining if the cost of repairs outweighs the cost of car payments + additional insurance cost (after factoring for depreciation). But there are other less tangible factors - how satisfied am I with my SVT? How much is being fully satisfied worth? Would I care for a brand new car better?
I should say that doing repairs myself nowadays just isn't practical. I work two jobs and am finishing my bachelors so I spend what little spare time I do have with my friends and family. Maybe my wishy washy post belongs in common interests...