It won't work correctly. It's not compatible.
You'll need to use the Minolta 2500(D), 3600HS (D), or 5600HS (D) for compatibilty with KM DSLR models (or you could use the new Sony HVL-F36AM or HVL-F56AM, which are the Sony versions of the Minolta 3600 and 5600).
An older Minolta strobe that's not compatible like the 3500 xi will fire at full power when used on a KM DSLR.
Because sensors are too reflective to meter from during a flash exposure like you could with OTF (Off the Film) metering, flash systems were redesigned for digital to always use a preflash, making the older strobes incompatible.
There are some third party altenatives like the Metz 54MZ series strobes using the correct SCA3302 M5 or M6 foot, too (and it can eliminate the need for a preflash while still being aware of the camera settings using it's auto feature with it's built in sensor to measure reflected light).
Or, you could use a non-dedicated strobe like a Sunpak 383 Super via an FS-1100 adapter to give the 5D or 7D an ISO standard shoe (you'd need to use manual exposure on the camera, setting the camera and strobe to match each other). Some of our forum members use this type of solution. I've got a Sunpak 333 Auto I use via a third party adapter with my 5D.
But, the older Minolta strobes aren't going to work correctly (they'd always fire at full power when used on a KM DSLR).