Win XP Pro on 800 MHz Processor?

I’m looking to upgrade RAM on some 5 year old computers so I can make an entire room Win XP Pro instead of a mishmash of XP and 2000. I know I’ll need at least 512MB of RAM, but can anyone tell me if they have experience running XP Pro on 800 Mhz Pentium 3 and Celeron processors? Was it ok or a dog? I’m concerned with speed…I don’t want the users to click and wait. Not running any huge programs – just browser windows and office apps mostly. Most of the time only 1 program at a time.

Thanks