This version of the Acer Aspire One comes preinstalled with Windows XP Home Edition. I'd prefer Professional, of course, but Home gets the job done. It sets up rather easily and quickly—I did it in the car while driving home from picking it up at the UPS hub (I wasn't driving, of course). It comes preinstalled with the usual garbage including McAffee and even the Google Sidebar; all of these except for the Synaptic touch pad software I uninstalled via Windows' Add/Remove Programs feature.
Startup is beautifully quick where login takes a mite longer than I'd expect, but it's nothing compared to how long it takes for my Vista desktop to log in, so I’m happy.
Internet applications run smoothly and I can access all of my preferred websites without any problems. I normally use Google Chrome but sometimes use Firefox when Chrome is behaving naughtily with a certain page. I have also used Lunascape, a browser previously reviewed on OSNews. Simply put: they all run beautifully on the One.
For several of my duties at my local school, I frequently use the Microsoft Office 2007 suite on XP, particularly Word, Access, and Outlook. All of these run without any real trouble, albeit somewhat slower than on my other desktop machine that I also use for the same purposes. Overall, they ran better than expected. A minor problem is that they weren't designed for a small screen--especially Access and Outlook--and I find it sometimes hard to use those two because the screen real estate is taken up by so many sections of each program (such as in Outlook: the reading pane, the email list, and the to do bar). Word has crashed several times due to errors with my network printer setup between printers on Mac and Ubuntu machines, but printers shared from other systems do not cause these crashes.
I give the Windows XP experience on the One a 10/10. It runs everything a netbook should be able to run and does it about as fast as you'd expect on a full-fledged laptop. It even runs some bulkier software such as Office 2007 nearly as well as on a regular lappy. Stellar performance, Acer and XP. Stellar.