Arcitecture Specific Programming

[DarkDragon1993]

Hello, dear Community!

At the moment, I'm digging into programming for x64 architectures. I read some articles on msdn for this. But now I was wondering, if I have to recompile my custom libraries to embed them in x64 projects?
Actually I'd just go ahead and do so, but since I found out, that I seem to build for x86 as well as for x64 platforms, I'm a bit confused. As far as my logical knowledge reaches, I think that I cannot embed both libraries for one project since I would have doubled references of functions.

If somebody could give me more information on this topic, I would really appreciate this.

I'm using VS2010 Professional. I've set the configuration manager to an x64 platform that inherits the settings from x86 platforms.

Could it be, that _M_IX86 is always set when targetting x64 platforms?
Or does VS2010 even manage this itself?

For example, I've read this following article as a source of my spare information: http://msdn.microsoft.com/en-us/magazine/cc300794.aspx

I hope to get more information and sources here... ;)

Sincerely, DarkDragon1993