Its probably due to all the downloading you have done since getting ADSL Lona
If you dont have much space left on your hard drive then your pc cant use as much as it for the Virtual Memory as it did before.
Delete any unecessary files and copy any downloaded stuff to cds and then delete the original, dont forget to empty your recycle bin as that takes up space too.
You could add more ram too but if it was ok prior to getting "download fever" then I should think that its hard drive space that it is needing more than ram