Printer/scanner

I bought a new Dell Dimension 8400 which came with a Dell 720 printer, I have been trying to use my old 4200C HP scanner, which looks okay when I scan in anything but when I go to print it is far larger than it should be, I have tried altering the output size, but then the quality goes.  Also when printing from web pages it missed out a section down the right hand side, everything looks okay in the print preview, but not when actually printing.  I also have problems trying to use a smaller size of paper, if I 'custom' the paper size it looks okay in preview  but doesn't print in the right area of the page.

Would be gratefull for any help on this, thanks