Upgrade of old Graphics Card that is compatible with Windows 10

I have a problem with installing Windows 10. I like many others reserved my copy of Windows 10 by the Windows 10 App. After a check of my rather old system Windows came back to say everything was in order and ready to go once Windows 10 was to be released. No...........on the 29th July I got word via the App that my Graphics Card a NVIDIA GeForce 6100 nForce 405 was not compatible with Windows 10 and that I speak to Nvidia.......or get a new PC.
No I don't want a new PC.....i have a 2014 iMac and I don't want to spend much more money to upgrade. So can anyone here suggest an upgraded Graphics Card that would be compatible with Windows 10 (and doesn't cost the earth) I don't do any gaming or video editing just surf the Net, watch YouTube Videos and listen to Music through my Bose Speakers....oh and sometimes watch a few Movies

Here is my old PC:-

It is an Acer Aspire T180
running 2.00 gigahertz AMD Athlon 64 X2 Dual Core
256 kilobyte primary memory cache
1024 kilobyte secondary memory cache
64-bit ready
Multi-core (2 total) with a recently installed Samsung SSD 850 EVO SCSI Disk Device (120.03 GB) and a secondary internal
Western Digitial 50 HHD Disk Device (500.11 GB) It is running Windows 7 Professional Service Pack 1 (build 7601) and it connects to the internet via a Edimax AC1200 Wireless LAN USB Adapter.

Can you suggest an upgrade for the existing NVIDIA GeForce 6100 nForce 405 graphics card that would be compatible with Windows 10 (and wouldn't break the bank)?

Thanks in advance

Harry

Upgrade of old Graphics Card that is compatible with Windows 10