small application in visual c++

I started to use visual c++ few days ago to edit an open source project ,SFX7zip ,inside the zip folder/release i got 2 exe compiled already(in the size of 27.5 kb and 19 kb(used upx)),

everythin开发者_JAVA百科g worked fine i tried to compile them (with VS 6.00 and VS 2010) ,both them gave me a big size exe (75 KB and 65 KB), i am sure that the pre compiled exes are not used other tools to compress (except upx for one of them , according to the help inside the zip) why these size are different for me

size is still a problem for me (even in this century ) and i am using it for a setup app,

what are the mistakes i have done when compiling (or what tool or what version i have to use to compile this source)