New PC - display weirdness.

Hopefully someone has seen something like this before.

I recently bought a partly built rig from scan, low budget for second PC/family use, web browsing, 16-bit software, older games that kind of thing. Unfortunately the graphics are acting kinda weird and I don't know how to diagnose or fix.

Rough specs:

4GB DDR3 RAM
ASUS AM1M-A mobo.
CPU: AMD Athlon 5350 APU with Radeon(tm) R3
On-board graphics (or would that be determined by the CPU nowadays) billed on the mainboard box as "VGA: Integrated AMD Radeon R Series Graphics in the API - Multi-VGA output support: HDMI / DVI / RGB port"
Windows 7 OEM 32-bit. Display reports the graphics card as AMD Radeon HD 8400
SSD and Blu Ray drives carried over from old computers.
Monitor is an older Dell monitor 1024*768 - VGA connection.

The problem is this: during boot-up and in Windows if I allow it to use the full 1024*768 display capabilities of the monitor, the pictures goes off to the left about an inch and a half, hiding the start menu button and things like that, while on the right there's a small back band maybe 3/4 inch wide.

There is a thing for positioning and sizing the display in the AMD, (screenshot attached) but that only helps a little bit, it narrows the gap on the right and brings back some of the hidden screen on the left but still leaves much hidden and a small back band on the right. Some of the buttons move the image, but only to a point, but some of the buttons look like they're supposed to do something but when I click them, the screen flashes and nothing else occurs.

The monitor has been used with multiple computers in the past at full resolution using its default positioning settings so I assume it is not at fault, I can also fix the problem in Windows by setting the display to 800*600 but that's not fun to say the least, not sure what else I can do except get a graphics card.

I've always been an nVidia man myself because the last time I had a Radeon there was other weirdness but nothing like this. Tempted to get a GeForce 720 or similar and try that.

Can anyone offer other suggestions?