The most important thing people miss are URL links don't count a lot for search's it has to be descriptive text links, for example your signature will be spidered but no one will be searching for 29FIVE Designs, people will be searching for designs but the percentage of design links you're up againsts makes your chances very low. A text link that said....
29FIVE Designs provide Helpdesk Support Software, Web Design, Network Contracting and Computer Consulting.
Would pop up in search's alot more.
A good example of this is type
logo sauce in google and you'll see this forum pop up, not because of the links going there but because the links are descriptive and linked between the two.