Can I play GTA:IV with Pentium D 3.0GHz, 1GB RAM, and an ATi Radeon HD 4870?

See, my processor and video card are far past the recommended specs. However, I am curious as to how my ram would perform. Its only 1GB and its on Vista. I don't have the game YET, but I have superfetch disabled and I will switch aero off and change the theme to XP theme. I will also close background programs. Would doing this make GTA:IV run 25 fps + on my specs?