I generally do not advise people to upgrade the operating system on an old machine. Your experience with Windows 8 seems to support that decision.

That being said, I have installed Windows 8 on several older machines and have not had the same nightmare as you. The worse thing that has happened is that the Windows 8 evaluation tool indicated that my 6 year old laptop would not support Windows 8. Ubuntu worked on it. The best thing that happened is that my three year old tablet convertible took a Windows 8 upgrade perfectly. It has breathed new life into my tablet. Boot times are very quick - 30 to 40 seconds. It does a much better job taking advantage of touch input (finger and stylus) than Windows 7 ever did. Upgrades happen in the background when the system is rebooted. It has never crashed and I have never had a problem with it staying on the network.
Installing Windows 8 Pro with Media Center on my 5 month old gaming desktop went flawlessly. Performance is superb. It boots up in 20 seconds. - a major performance improvement over Windows 7.

It's too bad your experience has been so poor.