Most channels runs acceptable well with intermittent pause except TV3 which will out sync voice and video too offten. I also noticed that the hard drive are runing quite often and constantly , that makes me thinking that maybe upgrade to 2G of Ram will at least improve all the channels but TV3(possible TV3 as well?). But as far as I know, the most significant bottle neck for Freeview HD is CPU and Graphic card and my CPU is almost runing as 100% confirms to that. So I am afraid such a upgrade could be just waste of money.
Looks like 2*1G PC4200 or 5300 for laptop cost something like 100 on pricespy, if that is the case, I think an upgrade is worthwhile even for a marginal improvement.
PS: I am using Windows XP and I think it is kind of obvious given 1G Ram on my Laptop.