Precision T5400 CPU Upgrade

I recently purchased a Precision T5400 with a single E5405 Xeon CPU. I'd like to upgrade to either dual E5450 (80 watt) or X5460 (120 watt) Xeon's.

I found a new un-used JD210 heatsink on eBay and figure that should work fine which ever CPU I choose. However the thermal output of the X5460 at 120 watts might be a bit much but do-able. I also found matched pairs of either E5450 or X5460's on eBay.

I would like to know if at minimum I can go with dual E5450's and the JD210 heatsink and your thoughts on going X5460's. The VRM is built into the motherboard from what I can see. I'd like to do it this week if possible. Hopefully you guys have the answers.

Thanks,

Erik