The problem is that the native resolution of the Samsung 943SN is 1360x768 (see here). the SiS video bios obviously doesn't know anything about it. it just adds support for 1440x900 and 1680x1050 (reported working resolutions).
there are three solutions to your problem:
1. buy a new computer without SIS chip
2. buy an add-on card without SIS chip
3. use Linux and its excellent 3rd party drivers