I sell expensive stuff on my ecommerce website to businesses and private customers.
I used to show only a VAT inclusive price however some of my major competitors where from the US and they advertised UK pricing without VAT, I felt at the time this made us look expensive because the US sites made no mention of VAT, even at checkout, even though their advertised prices where listed in £'s not $'s.
I switched our site to major on the VAT free price, but on every product next to the price it shows the VAT inclusive price in brackets.
Although I was wary about making such a change upfront, to be honest it had no impact on our sales levels what so ever.
As everyone else says, if your selling to private customers mainly and not businesses then I'd look at what your competitors do and follow suit, this probably means including the VAT on your pricing.
Hope that helps,
Darren