Hello Kummer,
Without the correct hardware (eyefinity/video scalers) this is tricky, however there is indeed a 3rd party bit of software called
SoftTH which is limited to DirectX9 titles only.
The last stable version is the latest release of V2, V3 is currently in development which may bring DX10 and 11 in the future, although progress in development does appear to be quite slow.
"SoftTH contains incomplete code for Direct3D 10 (DXGI) and Direct3D 10.1 support. For Direct3D 11, most functionality is missing, but is under development."
Check out our
SoftTH forum section for more infos.