Image Resizing Suggestion

Hi,

I have developed a website, and it has got pictures with high resolution, average size being 5MB. Quality of photo is very good, and attractive, and its needed as I made it for trekking organization. I checked Plug Ins to minimize the size, but found that most of them does not work for pics above 1MB (Free version).

I would like to know, what other option do I have. Does resizing from Photoshop would work better than these plug ins, or do you suggest me to buy the pro ones? I want to minimize the budget, so, wanted a suggestion before making a move.

Thank you,
Prabhat