I've been offered a good deal on a G4 Powerbook (400mHz, 10GB hard drive, Ultra ATA/66 at 4200rpm I think, 128Megs RAM)
Right now I'm using a PC, but I'm willing to switch because I've heard great things about Macs. I tend to use a lot of tracks of audio and I like my plug-ins too. So, I know I'd get more RAM and at some point, a larger hard drive. And also some kind of audio I/O, of course. What I don't know is how that particular hard drive will affect performance. At 4200rpm, is it just too slow to keep up, or is that a myth? Is there room/a slot for another drive in there? What is the best deal on a mininimum 2-channels of 24/96 I/O for this beast? Any other thoughts/advice/rants that you guys could share with me? Thanks in advance; this forum has been a big help to me on more than a couple occasions. Oh yeah...I have to decide by noon today!

Yes Spindle speed affects access time, and access time defines how much data can succesfully be written to and read from disc in a given period, thus determining how many audio tracks you can run.
since my reply is late i'll stop there, but if you need to know more about macs, or other questions, please feel free to ask, and keep posting!!! this is a pretty good forum, and seems to be peopled by somewhat less esoteric and snobby surfers, thus i tend to see replies that often actually mean something relevant rather than just another mac/pc row ....
goodluck
hope yopu bought the mac!!
max