SF 4.5 worked great on my XP machine.. aside from the app's inherent limitations. .i.e., no real-time preview, VST support or chainer, among others. The subsequent version (SF-5), had 'real-time preview', but there were other 'issues'. I recall VST plug-in support started with Pro 7, however in SF 6, I used a third-party 'wrapper' to run VST plugs . I still have both Pro 9 and 10 on my old XP machine, which run splendidly. SF Pro 10 also runs great on my Win 10 PCs and I actually prefer Pro 10 to Pro 11 (IMO, SCS forked-up the GUI for the Record and Plug-in chainer... </end rant>). Both SF Pro 9 &10 also came with the (Direct X) iZotope Mastering suite. I especially like the Multi-band Compressor an Exciter. That was a separate installation, serial code and registration though iZotope.. They do not run on 64 bit versions of SF or Vegas however.

FYI. I recently sold a version of SF 4.5, so prior, I checked to see if it would install OK, it did.. BUT ONLY from the installation disc and disc drive, the installation files by themselves could not be used, though I did not try a virtual drive with a disc image, which I suspect would. The registration code to unlock the program worked and did not require an on-line procedure. I do not recall what version required on-line registration. (or 'register from another computer on-line').. 6 or 7 I think.

Addendum: "Magix, who now own and develop the SF range, have only done so since version 10(?)."

- MAGIX Software GmbH, acquired the majority of Sony Creative Software (SCS) A/V products when Sound Forge Pro 11 was the latest version. Earlier builds of Pro 11 were SCS, subsequent builds were MAGIX, but basically the same except sales, registration, support and such were MAGIX
"As of May 20, 2016 Sony Creative Software has sold the majority of its products to MAGIX Software GmbH. SCS will remain a part of Sony Electronics and will continue to own and distribute its Catalyst Browse and Catalyst Production Suite products".

4.5 is the berries. I still use it on two of my XP machines. And I got it to run on Windows 7/32 bit. But no-go on Windows 10. So I went to SF 12 and 13.

4.5 works fine on Windows 10 (I haven't encountered any issues). The trick is to run the sfsetup.exe file as an administrator in the driveletter:\Setup\English\Sound Forge\X86 folder. I can get CD Architect 4.0 to install and run doing the same thing (but no actual burner support). SF does need to run as administrator as well.