Oh dear onlyme. You really don't know much about Linux of late. And BTW Citrix runs on Windows......
Ubuntu and Madriva are leading the way with desktops. Look at Compiz Fusion that comes as defalt with Ubuntu. It leaves Vista in its wake for eye candy and runs on far less poweful machines than Vista needs for its AERO interface. With the lack of need for AV/anti-malware etc and the fact that it is a 'properly' secured OS designed to be so from the ground up it suits teh un-geek home user perfectly.
Vista needs a very powerful machine to be useable certainly not something a £200 laptop is going to be.
In response to Glasgow guy. I'd leave those two examples that you posted alone. Whilst they might be OK for a very limited market I doubt they would suffice for your requirements.
for a new laptop your looking at ~£300 upwards. Even then I'd avoid Vista like teh plague (in about an hour I'm about to remove all traces of that stinking pile of poo from my laptop. I rarely use Windows for anything but I'm going back to XP media centre as Vista is really not worth the effort.)
For your £200 budget look at factory refurb stuf with a decent warranty and XP. You should be able to get something that will offer far more than those links.
I spent 10 mins and found teh following
itfactory.co.uk - Cheap laptops: Refurbished IBM T23 Laptop
Factory Refurbished - Ex Demo Laptops FROM STOCK,Information Technology Clear Limited
I'm happy to keep an eye out as I do get stuff offered all teh time.