I thought this command would be very useful: Example {OS=Win7,Vista} "%WpiPath%\Install\MyApplication\MyApplicationSetup.exe" will execute the command only on Windows 7 and Vista (no XP, 2000 and previous). I went to config. In commands, went to condition/operating system and it gave me {OS=Win8,Win7,Vista,XP} . Being a bit of a simpleton I just backspaced over the OSes I didn't want. Examples: {OS=XP,Vista} "%root%\Install\AV CoDecs\VistaCodecs_v641.exe" {OS=Win7} "%root%\Install\AV CoDecs\Win7codecs_v390.exe" {OS=Win8} "%root%\Install\AV CoDecs\win8codecs_v132.exe" This did not work as expected. I'm using windows 8 pro x64. WPI version 8.6.3 I can't remember now if it failed or skipped. The first one is not that important to me because I don't have Vista anyway. It would be nice to know if it works though. However: {OS=Win7,} "%root%\Install\AV CoDecs\Win7codecs_v390.exe" {OS=Win8,} "%root%\Install\AV CoDecs\win8codecs_v132.exe" Notice, I left commas in. This does seem to work. From config.js: prog[pn]=['CoDecs etc XP Vista 7 8, 32 and 64 bit']; uid[pn]=['CODECSQUICKTIMEFFDSHOW']; ordr[pn]=[1250]; dflt[pn]=['no']; forc[pn]=['no']; bit64[pn]=['yes']; cat[pn]=['Multimedia']; pfro[pn]=['no']; cmds[pn]=[''{OS=XP%comma%Vista} "%root%\\Install\\AV CoDecs\\VistaCodecs_v641.exe"','{OS=Win7%comma%} "%root%\\Install\\AV CoDecs\\Win7codecs_v390.exe"','{OS=Win8%comma%} "%root%\\Install\\AV CoDecs\\win8codecs_v132.exe"','{x64} "%root%\\Install\\AV CoDecs\\x64Components_v390.exe"','{x86} "%root%\\Install\\AV CoDecs\\MPC-HC.1.6.4.6052.x86.exe" /VERYSILENT /SUPPRESSMSGBOXES /NORESTART /SP-','{x64} "%root%\\Install\\AV CoDecs\\MPC-HC.1.6.4.6052.x64.exe" /VERYSILENT /SUPPRESSMSGBOXES /NORESTART /SP-']; gcond[pn]=['FileExists("%programfiles%\\MPC-HC\\mpc-hc64.exe")']; desc[pn]=['Video Codecs]; pn++; Notice how it has replaced the commas with %comma%. It seems to work OK, but I'm not sure if I have to leave the comma in for multiple OS choices and I can't find any documentation that seems to help. If you were here is SW Wales in the UK I would come round and fix mritters main computer for free. Please continue with the WPI. I really do appreciate it. Terry