1stly :
"beside i mac?" , so i understand the people who are standing on the side of macs are trying to preach the
"dual booting" option. so ANDY82 , at your own risk ok. this thread seems to be turning into another mac vs pc war.
it's like cars, a Nissan Fairlady was built for the speeding/racing with its 3.5l engine, and a Nissan Murano with a same 3.5 engine but bulked up as an SUV for spacious storage and family use. but would go slower because of the weight and aerodynamics.
If you were meant to speed, get one solely for racing.
If you were meant to enjoy space and power at the same time, get one to achieve its purpose.
you said "besides imac" means PC (you can't mean linux anyway.) and for music. so people like cheez and myself using a non-mac and for music usage will be speaking up. Cheez is doing heavier duty composition ram intensive purposes so he needs 8gb ram. 64bit OS.dual boot cos he uses it for Office I assume.I'm doing recording/mixing and have my own methods to mix heavily at low specifications at 2gb ram and 32bit OS windows XP.I single boot because so far my office use on this DAW laptop has not come close to failing.
do not get an audio interface which is NOT windows 7 friendly asio drivers. cos that's your other key to stability in music production.
so if budget comes as an issue Mac can cost, PC-laptops also can cost for high end to meet your purpose, unless you're talking about cheap desktop DIY parts assembled together for longer warranty and upgradeables but that takes away your function of mobility (if you need it).
we have successful rates of people using macs and people using PCs doing it for music. as much as we have high rates of complaints of ppl against PC (instability/breakdown) and Mac (the very famous hdd merciless failure without warning. I know 4 people that felt the wrath)
so end of the day, it's what you're comfortable with, you're the "driver" of this "vehicle". you're the killer using your weapon of choice. so in case if you haven't read, pls check out
http://tinyurl.com/diyrecording , cos I assume the next thing you're going to ask is which DAW is better