It looks like youre saving all of your menu images as GIFs. This is not good, becuase GIFs can only display a maximum of 256 colours at any one time - your shadows and gradients are 'dithering', meaning youre not getting the smooth shading or antialiasing you would get with JPG. Saving them as JPGs will eliminate this speckly effect.

Also, its very orange - I think you should work in some other colours.

PNG is the best format for line art & gradients. JPG can get lossy, blurry and pixelated - it's meant for photos primarily.

Your site is monochrome. It makes it hard to know what is what, especially on the homepage. Your body copy is red, your phone number's red, and worst of all, your links are red. The links need to stand out if someone is supposed to know to click on them. The alternative is they try to click on everything, or they think the first page is the only one.

Okay, I actially used PNG and purposely opted to dither them, one reason being i could not use a drop shadow without dithering and another reason i thought it looked good that way.
Well about the color, the aim was to give a simple and straight forward look

Its very orange. :0) Do you live in the netherlands? maybe look at other design websites. You will see a massive difference between yours and other agencies. I think you should start again with more of a critical eye.

You need to save as a 24bit PNG, and not an 8 bit PNG. 8 bit PNG has the same issues as GIF (lack of colour depth).

a 24bit PNG will also work - the main drawback is you cannot compress PNG like you can with JPG, so the filesize of the images will be much larger. the main advantage of using PNG is that it supports 8 bit transparency, meaning you can get a nice subtle transparency fade (256 levels), as opposed to GIF, which only gives you 2 levels (on or off).

The dithering drop shadow effect doesnt work well here - it looks like something from the mid 90s, the early days of the internet - not a good look for a professional, forward thinking web design company. also it causes problems when it interacts with the orange blend thing youve got going on in the background.

the actual layout of your site isnt too bad, its clean and easy to navigate. just too much orange! maybe try toning down the opacity of the background image too.