Shopping cart software

Software to use for existing site

[benji]

I am about to embark on adding a shopping cart facility to an already exisiting site.
The site already has loads of pages of info, and they simply want to sell a minimal amount of products (3 categories would cover it).

I am familiar with X-Cart, but this would be complete overkill for what the client needs, but I do wish to still use a software package (simplicity reasons).
They literally want customers to be able to purchase the few products available on-line, but keep the existing site looking the same.

Looking for advise please..

[ogletree]

Yahoo store is pretty easy. I know people that use it for their shopping cart.

[Valley wall wall]

Google will be helpful too IMHO.