Does Changing Host Affect SE Rankings?
 

What's the effect of changing the host of
a web sites to its SE rankings?
Does it affect to the "age" considered by
search engines?

Is their a problem of changing the IP address?
Do SEs give a speciall attention to IP addresses?

YES your host can have many effects on your rankings.
if you have a .com and want to target uk/fr/de markets then a UK/FR/DE host is mandatory to appear in the country specific pages

if your new host has loads of IP's banned because of spamming, and if you end up on one of those IP's, it might have an effect on your rankings

if your new host is often down, this will definitly have an effect on your rankings

if your new host bans certain spiders to save bandwidth, this may have an effect on selected SE

hope this helps.