I have a friend who's willing to sell me Crysis, but I'm unsure if the boxed version of Crysis has its DRM patched out. Google says Crysis Warhead still has DRM, but what about the original Crysis?

Crysis has SecuROM. I have the boxed version, but it's not collectors.

Does it have the 5-install limit?

I think it does.

don't take my word on it but I installed/reinstalled Crysis a few times on my PC and never did run into any limit. You do need to have the CD in the tray though. They could just dump the DRM after Crysis2 is released, would be the sensible thing to do. Or even put Crysis on GOG.com :)

Retail has a disc check. DD has a 5 install limit.
When Crysis was released SecuROM was still, very, very shit. After over a month of contacting EA support they gave me a EA Store Special Edition (I only had budget retail) and that didn't work either. One simple crack later and problem solved. No more crashing.

I thought the Maximum Edition was DRM free?

The original game has only a simple disc check. Dunno about the other editions.