Don't know about the rotating desktop, but the slow-down could be caused by overheating. The system will throttle back the CPU to reduce heat output.

There are many threads relating to this issue in 51xx Inspirons. Here's one to start you off:

http://forums.us.dell.com/supportforums/board/message?board.id=insp_video&message.id=150792#M150792

Hope this helps.

Thanks - sounds like a plan :smileyhappy:

I'll give it a go when i get home.

Don't know about the Volari card, but you should be able to find the nVIDIA GeForce FX Go5200 64MB card, factory reconditioned status with 1 yr warranty, for around £75 from third-party vendors. Cheaper on e-bay, with the risk that it won't work.

Doesn't need to go back to Dell.  I did the upgrade myself at home -- it is very straightforward, though you do need to remember to ground yourself to prevent static discharge from damaging the card or your laptop (e.g. by touching bare metal on a central-heating radiator, or a bathroom tap). Instructions are on-line here:

http://support.euro.dell.com/support/edocs/systems/ins5160/en/SM/palmrest.htm#wp1112455

If you don't like the idea of DIY, any self-respecting computer shop should do it.

Ref the overheating.  Once you've blasted your canned air through from the back of the 5160 (not up through the fan vent), try and see if there is still a matted layer of dust. With the leading edge of the laptop on a cushion or other soft surface, and the laptop vertical, look through the radiator grille while shining a bright light at an angle through the fan vent on the bottom of the laptop. With a little moving of eye and light, you should be able to see whether the grille is now really clear, or whether the dust has matted onto the grille thickly enough to resist the canned air.  If so, and if you don't want to open up the thing yourself, it's something to ask the computer shop to do while they are changing the video card.  The on-line service manual and the instructions in the thread I referenced in my earlier post should be more than enough for the computer shop techie.