You can't link and compile code for 64 bit with a 32 bit Laptop. You only can crosscompile upward. So a 64 bit can compile 32 bit, but a 32 bit can't compile 64 bit applications.
If you are compiling with 32 bit machine compiling 64 bit dll, you will need to check 64-bit compatblity option, While installing Visual Studio, please select the corresponding option, additionally some more stuffs will be installed, you have to check the compiler linker options also.
It is very much possible to compile 64 bit dll from 32 bit machine, and we do.
Oh yeah, you're right Joseph,
I think cross compiling at Windows is not possible. But I'm suprrised that is, and that Visual Studio has the support inside.
I found this on msdn, possible it's interesting for you. A very interesting topic : )