Hello, I have been reading all of your replies and will try to respond with my thoughts.
Basically, I am running a Pentium 4 3GHZ,3 Gig memory computer which has been a joy to use. It runs 2004 and 2006, and I have often thought about installing a Radeon 800XT pcie16 GPU which was optional for this computer, in order to run Trainz at a much better level. I have the drivers on a Dell disk. I think my current X300 is a full height card. Not absolutely sure.
However, just lately,it has been having trouble booting up to a black screen then shutting off with a blinking green power button, which I must hold till it shuts off, then press the on button again for it to boot up properly. (I have read in Forums about this problem, but usually it is a blinking yellow light. All the lights on the back of the case are green.(It does this about half the time now for about two weeks).
Also, Yahoo Mail has messaged me that I might need a new browser to use my email after Jan.30 2019 or it might not work properly. My current browsers are Firefox 50 something, and the last version of Firefox for XP is 52 something, which I have already downloaded in case of a last resort. I had the last version of Opera for XP, which was not fast enough. The current Operas are Chrome based and will not run on XP.
My other very good browser is Vivaldi (1.0.1) which works almost as well as Firefox for my dial-up needs. And I have one newer version available. I really like this computer because it runs all of my favorite games and programs without a hitch.
Linux would be out because I don't believe it will run all my programs without lots of work.. I had once tried Puppy Linux on a previous computer because it was good on dial-up on old computers.
I do believe that Windows 7 will be useful for quite a while, because look at my XP still going online. And running my favorite programs.
Also,you may not believe me, but dial-up has been a very good antivirus/malware because the bloody thing runs so slow that there's no time to load anything bad. I used to run an antivirus called Clamwin, but all of the warnings turned out to be false positives. And I do not open email attachments and have told my friends.
I went to John Whelen's Dell links. The 3020 is no longer available.
I really am not even looking to run 2009 or 2010, which I own and tried and did not love. Nor the newer versions. I have a need for simplicity.
My library's computer is an Optiplex 980 Core VPro I5) and is a medium sized case, Not large. Windows 7.Quiet.Probably needs a low height video card.. 3.20 Gig Speed. 4 Gigs memory. 4.9 Windows Experience.
I still think that a stock Windows 7 Pro,(or such) would have the best chance to run my programs. But I don't believe all of them.
Thanks, Bob P