A 4850 for a 15" screen? I'd either go for a cheaper card (4650, nVidia 9600) for such a small res.
If you however can push a 22 or 24 inch monitor in the budget, this would be a great setup
EDIT: and I'd go for a single 7200 rpm harddisk. More storage, less noise and almost the same performance if you go 750gb+