Ooo.. that feels so good!!! Eurika!!
I can't believe I actually fixed it... ok so if anyone else is having this problem this is the fix...
In the read me it tells you to execute ./configure from the command line. This actually prepares all the required files to compile the program (I think). Basically there are two lib directories within the "X11R6" folder inside /usr. One is called lib which is the default one that doesn't work. The other is called lib64 which must contain the correct extensions for the 64-bit processor (I'm really guessing now) all you have to do is this:
Open up the configure file inside the rdesktop src code in your favorite editor and find following code:
if [ $xdir != "/usr" ]; then
cflags="$cflags -I$xdir/include"
ldflags="$ldflags -L$xdir/lib"
rpath="$rpath:$xdir/lib"
fi
All you have to do is change the third line to read ...xdir/lib64 so you end up with:
if [ $xdir != "/usr" ]; then
cflags="$cflags -I$xdir/include"
ldflags="$ldflags -L$xdir/lib64"
rpath="$rpath:$xdir/lib"
fi
Now re-run the configure, then the make and finally the make install and it should all work
Hope this helps someone in the future.