I don't think it will like Spywareblaster, but MWB should be OK, as it doesn't run in real time, assuming it's the free version. I'm not sure what value Spywareblaster has these days, but FS will protect you anyway. I have FSIS running alongside Windows Defender, and they play nicely together, but neither have ever found anything. I also have Malwarebytes installed, and do a sweep once a month, but that always comes up clean too.