Why do want to upgrade?
If you were a gamer and needed the better graphics you'd have done it already. If you couldn't run the programmes you wanted because of the graphics or memory you'd have upgraded already. If you were running out of HD space you'd have bought an extra one. I don't see the point, therefore, in upgrading just because they'll fit it free, especially at their prices.
You probably don't have an AGP slot so your video card upgrade would be limited to a PCI card such as a Geforce 4 MMX420. A memory upgrade would be by older SIMMs.
If you really want a better machine get a new one. Due to poor sales the companies have slashed prices to the bone to move them. It's a good time to buy.