Is a Mac Mini sufficient to tide over from '07 MBP?

So here's my situation: I've currently got a 15" MacBook Pro, Late 2007, 2.2GHz Intel Core 2 Duo. For most things, this is perfectly fine -- I can browse the web, check e-mail, manage an iTunes library, etc. But I do some small video work for a high school marching band program I work for, and I constantly have to deal with sluggish rendering, playback, etc. in Final Cut Pro 7 and Adobe After Effects, and slow load times for high-res Photoshop and Illustrator projects. Sometimes, full renders can take nearly a day, and my MBP just misses the cut for Compressor 4 (as well as FCPX and Motion 5) system requirements.

I don't currently have a full-time teaching job, and once I do, I'll probably pick up a high end iMac or -- if they actually update it -- a Mac Pro. Until then, I've begun work on more video projects for the marching program, and the time it takes to render, compress, playback, etc. is still frustrating.

I'm considering a Mac Mini to tide me over (I already use an external 23" with the MBP anyway). I know it's the low-end of Apple desktops, but do you think it would be enough of an upgrade over a '07 15" MBP to warrant at least $600? Is an i5 and perhaps an additional memory upgrade to it going to be that noticeable an improvement over the Core 2 Duo-powered MBP I've got? I can technically afford the i7 one, but I'm hesitant since I'm hoping to get a job and a full blown iMac or Mac Pro within a year or so.

Thanks for the quick responses!

I didn't realize the i5 was that much of an improvement. As long a dual-core i5 can handle Final Cut Pro X (or even FCP7) significantly better than my Core2Duo can handle FCP7, I'll probably get the base model, and then upgrade the memory on my own. I wouldn't need the i7 in the Mac Mini unless FCPX really needs it to run smoothly, or if I expected to use it as my primary machine beyond this fall. (I'll probably keep it, but just as a secondary once I get an iMac or Mac Pro.)