SharePoint Server 2007 general system requirements
Processor: 2.5 GHz or higher (dual processor 3 GHz)
Memory: 1 GB RAM (minimum)
Hard disk: 3 GB of available hard disk
Operating system: Microsoft Windows Server 2003 SE, Windows Server 2003 EE, Windows Server 2003 DE or Windows Server 2003 WE later plus service packs.