|And does any of your hardware have make & model numbers so we know what you're talking about?|
Is it a namebrand system or custombuilt? What model motherboard?
What model AGP card? What make/model PSU? (430watts tells us nothing about it's specifications)
A brief google on your beep sequence gives video error as the culprit but you knew that already. Without detailed info we cannot know whether what you have are compatible components.
Goin' Fishin' (Some day)