Try Joomla 1.5 with Virtuemart 1.1.2 - Its Free! You need to install Joomla first and than go to the Virtuemart site or Source Forge and download the latest Virtuemart package and install it via your Joomla Admin panel installer. If you have Cpanel web hosting, you can install Joomla through an icon called Fantastico! Its Free and it works great ! Cheers
I've heard that VirtueMart is good for small sites but I'm not convinced it's great for large stores. At least that's what I gather from what I've read.
I've been browsing other sites too and Prestashop seems to be highly recommended just about everywhere.
Magento looks good on paper, but it sucks in implementation. It's really slow and has a very steep learning curve. It's just so sluggish. I recommend Prestashop. It doesn't seem to be quite as popular as Magento yet, but it's picking up speed. Seems like the developers are adding functionality pretty consistently.