Too Many Links from One Site to Another

Linking From Site

[radarroy]

Late last year I developed a PHPBoard that has seen tremendous growth over the past several months. This board complements my e-commerce site that currently has a PR5 and it ranked #5 in Google under the my most important keyword.

The board that I host now has over 5500 pages (never thought it would grow so quick and fast), and I want to add a link to my main website in the footer.

MarketLeap page saturation is showning that I have 4700 of these pages indexed in Google and 5200 in MSN.

What I am afraid of is now adding my main site to the footer of this website and have so many incoming links that it may mess up my Google PR and ranking.

Any comments and/or thoughts about this?

They are on different class C machines.