fitts

I bought a copy of P-51d from gamefly before I knew about DCS, I then downloaded the 1.2.3.9871 and fc3. I got a flag that said I couldn't install dcs over a newer version when I tried to install P51d in the same folder as fc3. The result is I now have two installs one in c:\program files, and one in c:\program files(x86). What can I do to get down to one install with fc and P51d in it? I am running win7 pro X64 with 32ram and 2gb video card.