my 1330 has the 8400m gs.. my gpu got fried and dell replaced the mobo. the new bios - a11 and the new nvidia drivers on the dell site address the thermal issue but i dont know how well they will tackle the problem..
as long as ur machine’s under warranty, u dont have to worry about anything.
regarding the size of the 1530, the length n width should be roughly the same as any other currently selling widescreen 15 inch notebook.. the height will differ. the 1530 has a tapering design.. thicker at the rear.. if you have any other notebook lying around, check its dimensions online, then compare it to the 1530 dimensions and you’ll know what to expect.