Firefox and Tor Browser work good on Windows XP with 512 RAM. Biggest issue is Flash in Youtube and webpages. And I always run with AdBlock Edge add-on.
The concern is longevity and portability of the notebook. If somebody here want to swap my HP Pavilion dv8000 (AMD Turion-64 2.0GHz, 1GB RAM, Radeon Xpress graphics chip, dual hard drives 100GB each) for Panasonic CF-29 in working condition I will do it.
Lubuntu is Debian based btw.
For me it is irrelevant that I don't receive some patch for unused component or some other thing. Critical patches will be released for WinXP just as there were patches for critical vulnerabilities for Windows 2000 after it's support ended. And 99,8% of people get their computer pwned by their own actions (grab your dick and double click downloaded picture.jpg.exe) rather than by exploiting 0-day in Windows.
I probably will go with the dv8000. When in rest I will watch nationalistic and patriotic video clips with my comrades on it's 17,3 inch widescreen. And educate them about nature of russian imperialism and how to better fight against it by aiming properly.