RSS vs. Webservice

[h_distler]

Hi

I am currently evaluating how to integrate and display products and
documents lists.
These products and documents lists are retrieved from an external
system.

I am not sure which option to use ?
Here are the requirements i want to fullfill:

-reuse these views also in other web applications
-customize the layout of the lists.
-Every list must be uniquly addressable (URL?)


What do you think Should i read those lists into an RSS Format or
should I program a webservice for that ?

Any help is appriciated

Thanx
Hanselmann