I've put a Radeon HD5450 into an E50 with no problem, running 2x 22" monitors. It's not a gaming machine, just office work so it's running fine, plays videos and live streaming very nicely. I only upgraded with this card for dual monitor capability, otherwise the onboard was just fine for what my customer needed.
If you were after a card for playing games then really you have the wrong base unit to start with and may be better to get a better base unit and then think about the graphics.