This is just my experience, but maybe it will be useful to someone.
I've used and loved Macs from back in the OS 6.0.7 days. The last
Mac I bought was a 266 MHz G3 system which is now running OS
9.2.2 and has 192 MB of RAM.
I got Reason 1 when it came out. It ran fanstastically well on my G3
and I did a lot of tracks with it. However, as I got more ambitious
I started to bump against it's CPU limitations. Sure, I can experiment
with overclocking it to 300 MHz but that makes me nervous.
Because of all the years I've had Macs, I have a million little and big
applications licensed for it: Microsoft and Adobe products, Koan,
Max, shareware and freeware stuff, and a bunch of MIDI files in
Vision format.
The thing that put me over the top was getting Live. Alone, it runs
pretty well on my Mac, but running it with Reason made me salivate.
However that combination really strained my G3.
So my choice was: get a brand new superpowered Mac G4 mainly
for running Reason + Live (and maybe + Traktion); or think
about getting a PC to do this.
I don't gig out and I have a rack in my studio, so I was not
interested in a laptop. After quite a bit of thought and research, I
done went and built mah very own Pentium 4 in a 2 high rack
enclosure. I needed to buy a special power supply and fans to
keep the noise down, but now the system is quiet enough that I
can comfortably compose with it. The nice thing is that since I
have Reason and Live licenses, it's OK for me to install them on
the PC as well as my Mac (although they won't be used on the
Mac any more, probably.)
The whole thing was about USD1500; partially because of the high
cost of the rack enclosure. It's configured this way: 2.0 GHz CPU,
768 MB of RAM, 2x80GB Seagate Barracuda IVs (running in
ATA100 mode), Echo MIA sound card. I'm running Windows 2000
(partially since I have a philosophical objection to the XP licensing
scheme) and the whole thing seems to run great.
I don't have enough time on it to judge of its stability, I'll come
back in a few months and let you know if it crashes.
Adios amoebas...