Nope, I don't believe thats a factor at all. Some of the worst websites (speed, uptime, and poor design) often have good PR's.
no, it will not put any impact on your ranking. however, if you have a geo targeted site and and you moving host to a diferent country, then there will be an impact. for example, if you have a co.uk domain targeting UK visitors, then moving hosting from a US server to a UK server will only help and vice verca
We just moved our site and it improved it. Uptime and access time is very important to Google. One downsize we have encountered is the dynamic web page execution time. Google is having a problem with it. The issue had something to do with the connect string we used was adding a time delay and Google could not access ~8,600 pages. Our Webmaster Tools was first to report this, otherwise we would have lost those pages. Test this out first. Oh, we went to GoDaddy for the new hosting.
I honestly don't think moving servers would affect your PR. I have had friends move servers and be able to hold their PR instead of losing it.
Uptime is very important, so if your site is down while your moving servers - Yes your PR will be effected. All of those people saying no, moving servers doesn't effect your PR - It does.... Moving servers makes a big difference as google may cache your old DNS servers and IP's - Causing the spider to null when it comes to your old server address.
I think a lot of people in this thread are talking about SERPs instead of PR. PR won't be affected by changing servers. Your search engine rankings may change though. With geotargeting, changing servers could make your website more or less relevant for different regions. When you change servers you often experience some downtime which the search engines do not like. When this happens they often temporarily penalize your website. Such a penalty usually doesn't last long unless your website has a history of poor uptime.
I'm going to have to stray from the crowd on this one. I don't think it's a huge factor, but it's definitely a factor. In my own sites, and customer sites I have noticed if you go with a big name host, where there are a lot of IPs, I have seen rankings drop. Like most things with SEO there is no way to really prove it, but I have seen it drastically with some sites. If you have a bunch of sites linking to you, and you join their host, and share the IP that's going to look bad. Not only that, just moving to an IP with a lot of other sites makes it harder to determine if you're running a link network. Don't even kid yourself, the algorithms look for link networks, and you can inadvertently get yourself flagged as that. Is it a factor big enough to tank your site? In my opinion, no. But it is among the things that should be considered. However, content is still king. Like most small penalties, they can be overcome by organic popularity fairly easily. Just make your site great and don't sweat it!
Moving to another server will not effect any Rank, also if move to better server helps on uptime, speed, band width etc. This will helps ranking idirectly