To respond in a focused and concise, the seven major factors that can influence the purchase or not a product online are:
1. Cost (accessibility)
2. availability
3. Form factor (size)
4. Features
5. Extensions (ie, ability to upgrade)
7. Customer Support
8. Delivery

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Web 2.0: from website to services
Reference: Shinynews Perhaps we talk about it more than we use it and still it isn't clear for all...