Moving from one server to two?

[BrandiDup]

Okie dokie, I think I"m getting ready to make the move in the next day or two. I've decided instead of using two low end servers, I'm going to go with one higher end server. However, I'm still a little undecided as far as what my best option would be. Which type of server setup would be best, in your opinion?

# Dual Xeon E5405 Quad Core (Harpertown) (8 cores total, 2.0GHZ per core.)
# 4GB RAM
# 4,800GB Premium Tier1 Bandwidth
# 160GB SATA Main Drive - Free Upgrade from 120GB
# 160GB SATA Backup Drive - Free Upgrade from 120GB

OR

# Dual Xeon 2.8Ghz HT EMT64
# 4GB DDR Registered ECC RAM
# 4,000GB Premium Tier1 Bandwidth
# 160GB SATA Main Drive - Free Upgrade from 120GB
# 160GB SATA Backup Drive - Free Upgrade from 120GB

OR

# Dual CPU + Dual Core Opteron 2212 (4 cores total)
# 4GB RAM
# 4,800GB Premium Tier1 Bandwidth
# 160GB SATA Main Drive - Free Upgrade from 120GB
# 160GB SATA Backup Drive - Free Upgrade from 120GB

I don't really know what the difference is between them and the cost difference is fairly negligible. They did tell me if I go with the XEON, I'd have about 8 hours of downtime since I'm currently on an AMD server and they can't do a swap unless I go with the Operton. Which, in the grand scheme of things isn't a huge deal, I'm more concerned about longer term performance. Just looking for a few outside opinions before I make the big move. I'm nervous