Can these games be played without VGA?
DMC4 is fine for single core processors. DA and SHH both say they require dual core processors to play minimum specs. You MAY be able to play with a 3GHz P4, but don't take my word for it. As for RAM, you enough for all those games. It also depends a great deal on your graphics card. For some sort of idea, I could run all those games, including Mass Effect 2, on Max settings at 1280x1024 resolution with an ATi Radeon HD3650 AGP graphics card.
Use this to find your card. It's a general guide
www.tomshardware.com/reviews/best-gaming-cpu-core-i5-2500k-amd-e350,2843-6.html warrenthatcher - 8 years ago
My apologies, this one is for GPU
www.tomshardware.com/reviews/radeon-geforce-graphics,2086-7.html warrenthatcher - 8 years ago