incrediBILL - 3:00 am on Jan 11, 2013 (gmt 0)
If you decide on PHP then run it on the far safer (from hacks) linux machine.
Seriously off the original topic but in what universe is PHP safer on Linux? Poorly written PHP scripts are actually the biggest threat to escalation on any server I've ever seen.
The .NET on Linux problem may be solved by MainSoft's Grasshopper doftware, but I've never tired it.
Anyway, this discussion is beyond the scope of Spider Identification.