My version of Midisoft Studio 4.0 came with a floppy containing an upgrade, STUDIO.EXE version 4.03. This is claimed compatible with Windows 98, Windows 2000, Millenium, and XP. I find it does run under Win2K. One has to replace the old STUDIO.EXE with the new one.
You can try running your old version (if you don't have the upgrade) in Win7 under the Win95 or Win98 compatibility layer. Make a shortcut of studio.exe, Right click, open Properties, then select Compatibility and select the Win95 or Win98 compatibility layer. This may work. You have to launch it from the shortcut.
A patched version 4 claimed to work under XP, and implied to work under Windows 7 32-bit was at midisoftDOTcraigedgarDOTcom. This does work also under Win2K using the compatibility layer.
My package also included a copy of Midisoft Studio 6.0 for Windows 9x. This is a slightly later version. It freezes under Win2K, even using the compatibility layer for Win95 or Win98. (I don't understand why a later version wouldn't work under Win2k when version 4.03 does, but there you have it.)
But it might work ok under Win7's compatibility layer for Win95 or Win98. (Win7 does a better job on some old apps than Win2k or WinXP, I've found).