I've been looking around for a while for a decent shopping cart, one of the ones that I have tested in the past is oscommerce 2.2, but this one takes so long to customise, echo cart is the same, but some of the features are better, but it's only compatable with echo, I'm not too sure if I start changing the coding to change it to 2checkout that I may be breaking any copyright.

I would like to here some suggestions of other carts that are very good, I'm basically looking for either a free one or one that is a reasonable cost. Not too expensive.

This will be used for selling computer products, DVD’s etc. It must be able to hold hundreds of items with pics, and a downloadable section where the customer can pay for downloads.

Also it has to be compatible with Paypal, 2checkout and worldpay.
If anyone has any thoughts on this or may be able to suggest a decent one, I would be grateful.

ps. found x-cart which is exactly what I am looking for, before I pay that money, I just need to know if there is a better one or one the same for less money, $100 or less.

You could try out Interchange:

http://www.icdevgroup.org/

OSCommerce is the best one out there for the things you want and it is compatible with 2checkout.com.