Travel Agent/Intermediary/Reseller

Here is a Drupal Site for Hotel Reservation running on Drupal 5.x.

http://www.eurobookings.com

This site has complicated third party integration and giga bytes of data synchronization. Site has been put to live with Drupal development help from Gloscon Team - http://www.gloscon.com/portfolio

Hi,
I´m wondering whether anyone integrated a solution such as WCTravel white label with Drupal - here is a sample site

http://www.res99.com/nexres/search/power_search.cgi?src=10004328&header=...

if so I would like to learn what turned out to be the most efficient way to do it - if not, some advise on how you would approach the matter would be appreciated.

best,
Jens