I have a dedicated server and have recently started putting each of my websites on separate IP address's as many of them link to each other as they are within the same category but they are all on the same nameservers, will this effect SEO of the websites?
You should prefer different name servers, however if the IP addresses are different, there would not be any problem. You will have to be more cautious only if you are willing to link your sites with each other.
Ip address main things then If you have multiple websites its better to have it in different servers.
Same category and same server does not matter because your site's IP addresses are different that actually matters in SEO.
ok great, really did not want to go and get separate nameservers for each website, that would cost a fortune.
Dedicated severs and static IP's a re the best thing to build a site but it create problem when you are trying to make multiple accounts with one computer as the IP doesn't change you have 100% risk of getting banned from any high page rank forum.
The problem with that is how much that would cost over the advantages of having dedicated server and also the cost implications.