Different Ips are great but even further they need to be on a different C block and also geographically. So it better to pony up the $$$ and set up separate hosting packages to be for sure you dont get linked as the same owner.
This excerpt from search engine watch is a pretty good explination of c blocks
"To make a long story short:
192.168.006.001
is a standard, fully qualified IP address. The blocks in this case are:
AAA.BBB.CCC.001-254
That's not a Typo - Class D and E look totally different. The last 3 digits are actually called the Rest Field
So these are within the same class C:
192.168.222.111
192.168.222.230
And these are different Class C IP's:
192.167.111.233
192.168.222.233
Note: A class C is not the only thing Google looks at to detect relationships - telling someone to "get a different class C" is not necessarily a fix for anything.
"
So this is just another thing to look at when creating your mini
network. Good Luck.