PhotoImpact 8 is an adequate program (I reviewed it in Amateur Photographer, October 2002), which will offer you more than Paint. It is very similar, in scope, to Paint Shop Pro and like PSP somewhat emulates the big one Photoshop.
Regarding resizing of images; downsizing is usually performed without a problem. However, increasing the size of an image can cause problems in that (depending on the start/finish sizes/resolutions) blocking can occur in the final image.
There is software specifically for increasing the size of images but this is of a Pro nature and is priced accordingly.
TFC Nothing is a problem for me...