Nothing wrong with old hardware! I have four Eee PC's which all have the Intel 915GM - and they were produced in 2008 and 2009 so 915gm was still being used only 6 or 7 years ago. I successfully upgraded one of them to Windows 7 (it had run XP previously) on a larger ssd drive - it installed like dream and Windows downloaded all the necessary drivers - the only one missing was the ACPI driver and that was available elsewhere.
Video Driver Vista
Downloads for Intel® Chipset Software Installation Utility. Download type. Any Download Type; Drivers. Windows 7, 32-bit*. Video/Touch > NC6120 Display Driver. Display driver for intel 915Gm on *Windows. The Mobile Intel(R) 915GM/GMS,910GML Express Chipset Family. Where can I find Mobile Intel® 915GM/GMS, 910GML Express Chipset. 7: Intel 915GM/GMS, 910GML (WDDM) drivers? Sort of problem video drivers help - new to Windows. Please note that I will always update the download link, so please let me know if the link is broken. GRAPHIC: Mobile Intel(R) 915GM/GMS,910GML Express Chipset Family For Windows 7.
Anyway my Eee PC has had the same compatibility message as yours about 915gm. I haven't tried to upgrade to Windows 10 but I had read of someone upgrading an Asus 1000H to Windows 10 successfully and that also has 915GM. Our other netbook - much more modern does not have any incompatibilities highlighted but the upgrade to Windows 10 was unsuccessful as there is no graphics driver for it. Intel only made it to run with Windows 7 and nothing else (this is a more modern Cedarview processor only about 3 years old).
So age isn't necessarily the issue. If you want to try upgrading it I would do the following, Make back up of all your personal files - eg documents, music, videos, photos, downloads - on a portable hard drive or large usb sticks. Make sure you have made recovery discs (via Windows 7 backup and restore) and a system image (also made via Windows 7 back up and restore - you'll need a portable hard drive to make the image). Ideally you also need Manufacturer recovery discs or a Windows 7 disc with product code for a clean install (in case the system image won't restore for some reason). Only then would I try upgrading to Windows 10. Intel have not made an upgraded driver for 915GM for Windows 10. There may be one available somewhere if you google 915gm - Windows 10, that other people have found.
Intel 915gm Express Chipset Video Driver Windows 7 Download
If you don't fancy manually installing a driver, I wouldn't bother trying to upgrade - Windows 7 is supported for another few years and I prefer it in many ways.