Can't use VR mode

[Mutated Plush]

I can't seem to use Steam's VR mode, and no matter what I read it's impossible for me!

I have tried putting -vr in the command line (which I assume is the Target), but it only allows me to do "C:\Program Files (x86)\Steam\Steam.exe" -vr, not "C:\Program Files (x86)\Steam\Steam.exe-vr" or "C:\Program Files (x86)\Steam\Steam.exe"-vr.

I have enabled SteamVR for the beta and made sure my actual steam was enabled for the latest beta. Could anyone help me?

My Specs are
GPU: GeForce GTS 450 (1GB)
CPU: Intel(R) Core(TM)2 Quad CPU - Q6600 @2.4GHz (4 quads, 4 threads)
Memory: 8.00 GB RAM
Current resolution 1280x1024
Operating system: Microsoft Windows 7 Ultimate
Motherboard: IPIBL-LA