Well, from my experiences, i have an Acer 5110 (dual core amd 1.6, 2gb ram, ati x1300 dedicated graphics) it came with vista home premium. It only took half a week before i "Upgraded" to XP. Vista is slower, less user-friendly (requires tons of excess clicking), and plain annoying to tech savy users.
Anyone that says battery life is better, i highly doubt, by default you simply have tons more background processes running at startup.. I have 28 on my laptop (thats including Anti virus, gtalk, graphics card utility, and a few others...). I see many vista laptops with 70+, thats disgusting. Sure you can disable the default visual effects, sidebar, system restore, UAC, etc...but there goes most of the new features of vista!
Also, if you want some fancy effects for XP, look for the
Vista XP theme that microsoft removed ... (but it still around on the net if you look for it...), google widgets, Expose alternative for windows or Microsoft powertoy Alt-Tab replacement as well.
Even though Toshiba may have drivers posted for Windows XP, be prepared they may not work (they are often much older versions). Acer only had a generic wireless card driver for xp and it didn't include a proper utility for managing wireless connections.
The IMPORTANT part is, while in Windows Vista, write down (or save a report in
Everest Ultimate) of all the hardware (in device manager), including model numbers. (Video, Network, Sound, Flash Reader, Wireless, etc).
I forgot to grab the model number of my atheros wireless card (because i assumed the acer driver would just work), which they didnt. And it was hard to find a utility that would be compatible without the model number (trial and error!).... If you need an atheros utility that works good under XP let me know...
Ubuntu 8.04 is nice (and 8.10 is out)... very user friendly debian based linux and dual booting is very easy to do using the Ubuntu Live CD. Again, wireless was the only thing that was tricky, but theirs tons of friendly people on Ubuntu forums to help you out.
-Kevin