Seperate Hosting Needed?

Is seperate hosting required to prevent penelties.

[printergal]

Hi,
I preface this by saying that I am very much the novice.

I run two sites that sell widgets, both hosted with the same firm (and so I presume on the same C-class). I am looking to start a review site of all widget sites, this will obviously link back to both my sites (and in order to get it started no doubt visa versa) - note this is not intended as self promotion.

Am I right in thinking that the sites risk being penalised by Google if I host the review site with the same provider as my present two sites?

Thanks in advance,