MacBook Pro :: MacBook Pro Cost/Benefit To Repair Old, Or Sell And Buy New?

I have used a Apple MacBook Pro 2.0GHz Intel Core Duo (15.4-inch) for the past four years of college. In that time I've had it repaired once for some spillage, but other than that nothing has been done. The laptop has recently been showing serious age. I don't have a ton of extra cash, and was wondering if it would be smartest to A) Buy piecemeal repairs, and fix this one or B) sell/scrap this and purchase something new. I don't know the numbers enough to do a cost-benefit, so any help would gladly be appreciated!


INFO/BACKGROUND

Apple MacBook Pro 2.0GHz Intel Core Duo (15.4-inch) Bought in Summer 2006

? Track pad seems to be breaking/broken ($ fix cost?)o Does not click appropriately
o Frequently messes up typing when barely touched
o Extremely finicky? Screen sometimes displays lines of messy black lines in the middle of images with no rhyme or reason ($ fix cost?)o What in the world could be causing the screen to display improperly in lines?
o Is this a video card failure?
o Is memory too low?
o Is it the logic board? The battery is 100% dead and useless ($ fix cost?)o Laptop must be plugged in to work? Slow, and seemingly inconsistent performance ($ fix cost?)o Memory/ram was never updated
o Safari has to be opened twice to work, first time it always just sits there
o Microsoft Office 03 applications run at a snails pace? Still running original 2006 OS as well as all old OS applications ($ fix cost?)

? Case shows signs of use along edges with separation ($ fix cost?)

Also, if there are any ideas on what this would sell for, or a total cost to get it into solid running (and lasting!) shape would be awesome. I'm at wits end trying to budget for all this -