Other options:

PHP Shopping Cart Software: PayPal, Froogle, Mals-e Free shopping cart download trial

Shopping Cart Software by ClickCartPro Ecommerce Solutions

Coldfusion Shopping Cart Software - SiteDirector Storefront Software

ASP based:

CactuShop ASP Shopping Cart 6 - Ecommerce. Full CSS support XHTML. MS SQL, MySQL, Access db. Skin system for...

The Template Store will sell you a copy of their css/xhtml storefront - with the ecommerce engine:

CSS shopping cart software ecommerce templates from The Template Store

And - BTW - it is possible to get the catalog side of OSCommerce compliant:

osCommerce: valid XHTML Catalog Side 2.3

__________________
:not_the_usual1
[you decide]
________________
All in my opinion, which, when combined carefully with a $1 bill, gets you a cup of coffee at the corner store.