Are my outgoing links on each page are bad?

The outgoing links are link to Ebay and Froogle

[kanwairen]

I have a website; I sell some goods on it. It’s a six month old site, I use google sitemap, and the site is almost indexed in April. However , things went to bad in May , almost all the pages become Supplemental result .
All I did to the site in April is that I added two outgoing links on each page , one to Ebay and one to Froogle, I wanted my customer can compare our price to the price on these site.
For example , on my page sell mp4 player , I’ll add a link to Froogel #*$!.com/froogle?q = Mp4 player and a link to Ebay #*$!.com/Mp4 player .
Does this damage my site? Can anyone help me? Thanks!

[Tinus]

My experience is that sitewide relevant links don't hurt.
Your site is young, 6 months. In the first year many sites get troubles. If you have enough inbound links and good content, SERP will improve later for you. Alas young sites are depending more on Adwords then old established sites.