How do I run a command line if statement in a PowerShell script

I have the following PowerShell command that is working...

& "C:\Program Files\MyProgram\MyCMDprogram.exe" -Enable 7584345

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But I want to test for the computer name.  If I add an if statement like this...

& if %computername%==xyz123 "C:\Program Files\MyProgram\MyCMDprogram.exe" -Enable 75843456

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It fails saying that "The term 'if' is not recognized..."
How can I run this command in PowerShell?  In a batch file, it would look like this...

if %computername%==xyz123 "C:\Program Files\MyProgram\MyCMDprogram.exe" -Enable 75843456

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