On Mac Hardware...
Would it be cheaper... NO, not really. see below.
If you want a Laptop that just plain works... get a MBP (Mac Book Pro).
On "desktop" machines... the Mac Mini is "good enough" but it will show its age quite quickly.
The Mac Pro... new == spendy. For current stuff stay away from the G4 and G5 models... I've seen some 8GB, G5 2.0GHz Dual Processor, gaggle of disk go for $400. But then the latest OSX you can load is 10.5.x which is going off support in a year or so.
Personally, I'd go and get any Core 2 Duo 15" MBP with 2+ GB of RAM and as big a hard drive as you can get if you want. Go and get the 10.6.x update from the Apple Store and buy Final Cut Express at the same time (iWork is great also).
You been suffering through ancient machines as it is... you'll be thrilled and Stuff Just works with it. 2.0Ghz+ Processor Core 2 Duo machine and 2+GB of memory will thrill you to death... and be cheap enough to last long enough for you to get a new one when you are ready and one last thing... don't forget a "time machine" backup drive in a USB case or some such. "Time Machine" is damn near perfect.
