Let me start by offering my condolences for running Vista. You may do yourself well to look into hopping on up to Windows 7 post-haste. I highly recommend it
While Beefy is right and your 64-bit OS should be able to run any 32-bit software, there are a few tweaks you can try to coax it along.
First, right click the application (shortcut or otherwise):

Then select Properties.
Then, you can try to run it in a compatibility mode with a previous version of Windows. Click on the compatibility tab and select the check box for 'Run in compatibility mode for:' and then click the drop-down box for a list of choices as far as which OS you want to apply. Start with XP SP2 and work your way up. You may not see the same options as I am running Windows 7 Pro here.
Then, you may also try running it as the Administrator. This has fixed quite a few functionality things with Vent and CoH in the past for me.
When you're all set, just hit apply and see if it works.
To help us further can you tell us the app and the actual error you are getting? That, along with the other info requested will assisit in hunting down the issue here.