New iMac vs Powerbook 15"

Hi.. I am a college student looking to purchase my first mac.

I currently own a pretty solid Thinkpad that could continue to be my mobile system if need be (would need new battery and maybe extended warranty though, so about a $250 expense).

I have narrowed my choices down to the iMac and Powerbook 15" because I do like laptops (used them exclusively for last 5 years), but feel that the processors/video card/screen size/HD speed/bus speed difference between iMac and Powerbook must be quite large. I am not sure exactly how to quantify it though for my needs as I am not that knowledgeable in mac hardware. I am going into my senior year, so I could see myself getting an iMac because it is more powerful, but still easily transportable for the various times I will be moving in the next 12-14 months (winter break -> home, winter break -> college, graduation -> home, home -> new job location).

My most intense use would be Photoshop, and whichever system I get I would max out the RAM to 2GB. Along with this would be my film scanner. I shoot a lot of pictures and handle a lot of scanning and then post-processing work in Photoshop using my Wacom tablet.

At the same time I am a bit of a 'power user' in that I am a CS major and find my life/work revolving around my system. I almost always have a browser (with about 4 tabs open)/chat client/file explorer window/music player all open at once, on top of anything else I may be doing such as photoshop or writing code locally/ ssh'ing to run it.

I have not installed a computer game on my system since high school and don't plan to now. I do not do any video work, nor do I plan to. I do webdesign work occasionally in dreamweaver, and very rarely some Flash work. I do frequently back up my data to an external HD, and will also be burning DVDs with some frequency (weekly/monthly). I would be getting the iWork suite on either system for Word Processing + Presentations.

I guess my question in this whole mess is... will a 1.67ghz G4 15" powerbook w / 2GB of RAM cut it...or should I go for the 2ghz G5 17/20" iMac w/ 2GB of RAM?

Also, if the Powerbook would suffice...what purpose would the $90 upgrade of video RAM server for me, as a non-gamer, if any? I know in windows systems as of right now, it would have very little effect..but what about OS X with Core Image?

Of course my purchase will not be until august so I have my fingers crossed for even a slight powerbook upgrade (every ~6 months??) to make my decision easier...

mate a PB would be quite at home doin that it just depends if you need the mobile aspect

if not id go for the imac personally as they have just been updated

I don't know how wedded you are to the prospect of portability, but I certainly was when considering what I will be upgrading to from my Mac Mini so I also figured that a Powerbook would be just the ticket. Problem is I'm a real stickler for screen resolution. On the other hand I'm not too keen on the all-in-one design and minimal upgradability that the iMac has. (Though to be fair, a Powerbook is kind of an all-in-one in its own way.)

However I went to the Apple store yesterday, and after playing around with some of the powerbooks and thinking 'okay, these are pretty nice' I came across a 20" iMac. That thing was NICE, with a slim design and clear, high resolution widescreen with lots of screen real estate. Screen real estate is something you really want when doing photoshop work, that's why a lot of pros go with multiple monitor setups. Between the beautiful screen and sleek, sexy design not to mention that it's a G5 rather than G4 (and since the update a rather speedy G5 at that) my decision was made. I could sacrifice uber-portability to have something really awesome to come home to. Stupid work intel boxes I have to deal with during the day.

You should, however, go to an Apple store or other authorized retailer if you don't have one in your area and actually experience both before making a descision, because either way it's a big chunk of $$$'s and you don't want any remorse. I have a Mac Mini at the moment because the expenditure was fairly cheap to get into the Mac world if it didn't work out. In this case it worked out, but if >US$1800 was at stake you can bet my research would have including actually touching the machines.