MacBookPro replacement?

Funny whirring sound the other day on early 2008 MacBook pro. I had just moved important work related docs to dropbox when it shut down completely. On my way to Apple (passenger) for genius appt. If it isn't fixable, looking at a new MacBook pro or iMac. Don't absolutely need portability. Use Lr3 and PSE9 for photo processing RAW files. Do a little video with Canon7d but not much. Would appreciate your input re specifications etc that you might recommend. I usually research big purchases very thoroughly but hard to picture being without a Mac (and access to files on the hard drives) for long.

Thanks for whatever help you can give me here....

As an aside, happy to say that I had just purchased a 3rd big external hard drive to make Time Machine happy and have had it running the past few weeks. Phew!