Need advice Macbook Air 13" or Macbook Pro (use it for Garageband)

Question

Being that I have other Apple devices now I am also considering an Apple laptop.  I went to the Apple store a few weeks back and was really interested in the Apple Macbook Air 13" model.
My requirements are:
- portability (even thought I will not travel with it much)
- use it for personal email and browsing.
- use it for work as well.  I work from home so I would use it in conjunction with my work laptop which is windows based. 
- Do recording using Garageband. (I find the iPad just doesn't have enough tracks)
- Will also install windows on it for occasional use but for the majority of the time will run in the native mac OS.
- I am not a big gamer anymore but may purchase the odd game now and then.
- Don't intend to watch DVDs on it.
- All my files are stored on a Windows Home Server setup at home so will access most files from my local LAN.  Therefore not looking to store a huge amount of data.
However one of the Apple Reps told me that I really should consider the Apple MacBook Pro instead as it has more power and expandability in addition to a bigger screen (15"). I seemed to be someone sold on his reasoning and was leaning towards a Macbook Pro.   I am not sure that having a bigger screen is a must have but maybe so for Garageband. 
Therefore it would between:
Macbook Air 13", 8GB internal, 256GB Flash = $1599
Macbook Pro 15", 8GB internal, 500GB drive @ 5400 rpm = $1899
And if I went with a smaller screen.
Macbook Pro 13", 8GB internal, 750GB drive @ 5400 rpm = $1499
Is there someone out in the community that had a similar consideration before making your purchase?  Will I have performance issues with the Macbook Air? Any advice or things that I should consider.
Thank you.

Answer 1

1) I used to use BootCamp but switched to Parallels Desktop exclusively a couple years ago. I have a couple programs for work I have to run in Windows and a web app that runs only in IE. Parallels works for me, including when I have to use Access or MS Publisher. I use Mac Office and only keep Win Office for the few times I must access a Publisher file or use Access. Parallels gives you a month to decide so I'd say go for it and see if it works for you. The big advantages are being able to run Windows and the  Mac OS without rebooting and that your Windows virtual drive can expand as needed. With a 256GB drive you'll want to be very careful about not wasting space and with BootCamp you must allocate a partition which isn't always easy to resize.
2) It depends on when you buy and where you buy. Apple's in store stock turns over very rapidly so a week or two after ML ships you should be able to get it pre-installed. If you buy online you are getting it straight from the factory so it should be pre-installed almost immediately. Other resellers turn over stock more slowly. If it isn't pre-installed you'll get instructions for how to download it. Lion was an hour download and 30 minute upgrade for me last year.
3) Typically Apple supports its hardware with new OS upgrades for about 5-6 years. Mountain Lion surprised us by dropping a couple computers earlier than that but the determining factor for ML seems to be 100% 64 bit architecture and some graphics architecture. This site talks about what isn't supported. All 2009 models are supported.
4) Every once in a while you run across someone complaining that his/her Thunderbolt-Ethernet dongles isn't working but I know of no one who has had trouble. I'm 100% wireless at home and mostly wireless at work so I can't say.
5) I have a Samsung digital at home and an NEC vga external display at work. Two different dongles but... I came across a very old NEC (probably pre 1995) projector I couldn't connect to, that's the only problem I know of. I see lots of connection problems at work mostly due to issues between the keyboard and chair, not hardware or software.
6) What is total performance? The truth about processors is that just about the time a processor is replaced by the next new thing software and language developers have caught up with the new technology. I waffled on the i7 and chose against it for my MBA. The speed increase doesn't seem to be that significant and I'll be replacing the computer in 2 years. When I replace my iMac later this year I'll go with a processor upgrade because I intend for it to last longer.