DICE has posted up the minimum and recommended requirements for Battlefield 3 Beta:
Minimum System Requirements
Os: Windows Vista (Service Pack 2) 32-Bit
Processor: 2 Ghz Dual Core (Core 2 Duo 2.4 Ghz Or Athlon X2 2.7 Ghz)
Memory: 2 Gb
Hard Drive: 20 Gb
Graphics Card (Amd): Directx 10.1 Compatible With 512 Mb Ram (Ati Radeon 3000, 4000, 5000 Or 6000 Series, With Ati Radeon 3870 Or Higher Performance)
Graphics Card (Nvidia): Directx 10.0 Compatible With 512 Mb Ram (Nvidia Geforce 8, 9, 200, 300, 400 Or 500 Series With Nvidia Geforce 8800 Gt Or Higher Performance)
Sound Card: Directx Compatible
Keyboard And Mouse
Dvd Rom Drive
Recommended System Requirements
Os: Windows 7 64-Bit
Processor: Quad-Core Cpu
Memory: 4 Gb
Hard Drive: 20 Gb
Graphics Card: Directx 11 Compatible With 1024 Mb Ram (Nvidia Geforce Gtx 560 Or Ati Radeon 6950)
Sound Card: Directx Compatible
Keyboard And Mouse
Dvd Rom Drive
And just so everyone knows your stats will not carry over from the beta, boooooooooo
Source Link: Battlefield 3 Beta Page