Look into SDL and S2DL as well. With those you can create an SDL window of a specific size. Also if your running in OpenGL mode you can easily setup scaling to 2.0 and have your rendering surface at 320x240 with your display surface at 640x480.

As for DirectX components, Dan JetX, Asphere, Omega, and many more exist. The latest version of DelphiX is pretty much unDelphiX .7 if I remember properly. Search the forums here and you can find the home page/download link. .8 is supposed to be out some time soon (at least according to the post).