by mh » Sat Sep 10, 2011 9:01 pm
You don't need MASM if you're compiling with Visual C++ 2008 or 2010 (don't know about 2005) - it comes with the download already (even the express versions).
Personally I just GAS2MASM the files, pull the resulting .asm files from the output folder, include them in the project (selecting the appropriate build rule when prompted) and junk the .s files entirely. There's a bit of massaging needed for some of the software Quake stuff where some jump labels have the same name aside from case, but otherwise it's clean.
Quake II used inline ASM in it's software renderer which might be worth looking at/copying from (I reckon that if you're using MASM in the first place then the added portability is low on your priority list).