[SiteShrine]

If you are considering osCommerce then you should consider creloaded. The templating system is in place and many of the modules you would need to add manually with oscommerce are standard with creloaded. Osmax is another option of oscommerce that has been improved upon.
Creloaded is a shopping cart powered by the popular osCommerce programming and supercharged by CreLoadeds added features and conveniences. This is the optimal cart for any eCommerce retail business venue. Easily manage an online store with a full featured shopping cart with inventory control, ease in adding inventory, seo control and capability, and tracking monthly sales and real time site visitors.

Create New Account or New Order
Edit Orders 1.56 MS2
Purchase Without Account
Free Shipping logic enhancements
Shipping Modules (UPS, FED EX, USPS)
Shipwire order fulfillment integration
Attribute Copier
Category Box Enhancement
Cross-Sell
Custom Sort Order
Daily Products Reporting
Download Controller
Easy Populate
Product Extra Fields
Customer Edit Page
Customers Not Validated Report
Purchase Without Account
Basic Template Structure
Category Box Enhancement
Template Install & Configure V1.2
Banner Manager
Credit Class / Gift Voucher / Discount Coupons
Header Brand Manager for catalog logo and slogan text
Print Order with Store Logo
Featured Products
Meta Tag Support
Specials On Main Page
Specials by Category
All products and manufacturers
Shop by Price Filter
Header Tags Controller
Article Manager
Information Pages and Categories
Links
FAQ Manager
Who's Online InfoBox
Language File Editor
Wishlist
Admin Dashboard
Admin SSL
Admin With Access Levels 2.2
Create New Account or New Order
Admin URL return after log-in
Mysql Backup
Product Notifications Reporting
Wishlist Reporting
Sales Reporting
Monthly Sales & Tax 1.55
VVC Configuration (on/off and settings)
Registered Globals Off
Order Fraud Screen
Visual Verify Code (VVC) security
SMTP mail server abstraction
Runtime Code Inclusion Expansion
Shipping & Payment Modules
Multi-language capabilities

The fact that you can install easily from Fantastico is certainly not the best reason to make a decision. The other carts out there are easily installed via ftp and include and install module with simple instructions. Even better is to purchase an upgraded version so that you have grounds to demand support for what you paid for versus hoping there is support with a free script. Shopping carts are always being updated as they have many functions that can become vulnerable to hackers. Don't rely on a free script where you have to wait for some generous programmer to update and contribute his findings.