Was reading some of your posts on other sites.
You do not have to use win7, it is garbage anyway. Use win XP. I have stopped to use any win above win XP. Win 10 or win 8 is one BIG SPY, and I do not care where they send the info about me.
Was using win Crystal for a long time, was good for modem tweaking, but microsoft forced developer to issue next releases.
But there is quite a few versions of win xp developed most recently, with plenty of preinstaled software and utilities. And of course you have the options which utilities you want to install.
And you may find some powerful utilities about serial port, worth very much to consider in your applications and tries to mod the bin.
Here you find site, where you can find all latest downloads of win XP, and other win above, and also linuks, BSD and plenty of utilities.
Win XP red, win XP professional, win Vortexjust to name a few....