I have a 24" iMac as a dual-boot (OSX/Vista) desktop, a 15" Dell laptop (XP SP3), and a 32 Gb iPod Touch.
They all fulfill their roles.
I’ve tried using some sub-compact laptops from friends, and IMHO they all seem to have the same problem (well, not really a problem but it’s more like cons). They always seem to be just big enough to make casual, truly-mobile Internet browsing difficult (like on a train/bus/subway/lobby/Starbucks/etc), but just a little too small to make doing real work in them difficult (I don’t like their small resolution screens).
While compared to a regular cell phone, the iPod Touch’s 6-8 hours of battery life when browsing the Internet or watching videos may not seem like much. However it pretty much far outnumbers nearly all sub-compact laptops.
And then when it comes to portability, it seems that anywhere you can take a sub-compact laptop would be just as easy to take a regular laptop. IMHO, the difference of a pound or two never really seems to matter, as most of the time it’s stuck in a bookbag with 20 pounds of other books and stuff.
Also, the mini keyboards in many sub-compact laptops are annoying as anything to use. They also seem to have the same Goldilocks issue of being just not right. Whereas hand-held devices like Blackberries or iPod Touch/iPhone make it easy to type with only your thumbs, and laptops make it easy to do full regular typing, the sub compacts are stuck in the middle. They are often too small to try typing regularly on, and are cumbersome to try the thumbs-only hunt-and-peck.
But at the same time, I love my iPod Touch. It’s just so easy to stick in my pocket, and check/write email every now and then, or go Facebooking for a while, or catch up on the news when I’m at my campus dining hall, or look up stuff professors talk about in lecture that may not have been in the textbook without having to whip out my laptop (some professors don’t like laptops at all during lectures since they can distract the people behind you), or watch episodes of The Office while on lunch break at my prior summer job. Also, the App Store is your best friend, especially in the games department.
Also, it’s just so much more convenient to have an iPod Touch with you than a sub-compact laptop, for those times where you spend a few minutes waiting for a train or in a hotel/hospital/etc lobby. Even if there is no wireless internet, the iPod Touch also have some amazing games in the App Store.
However, I’ve met others who love their sub-compact notebooks to death. Really, what it takes is to find someone or store that has the sub-compact in question, and use it. For like an hour or more, to fully find out what it is like to use it. Then go to an Apple Store and use an iPod Touch for a while. Then make a choice based upon that.
If I had to make a recommendation, I’d say that since you already have a laptop, go for the iPod Touch.
