Just how much do you want to spend to get how much improvement in your lights?
The HID lights will be the best part of £200. I have got some, still to be fitted from www.hids4u.co.uk and he is very helpfull to deal with. They put out a lot of light and look a cool colour. Alignment must be right!
For less money use the Philips 50% better lights, forgotten the proper name at about £14. They do perform better, I have them in the cally (compared to that you have fantastic lights! For a bit more light put the dipped beam on a fused relay fed straight from the battery.
Alternately for about the same money you can use the Halfords high power 110/90 or 80 bulbs again with a relay. Strictly speaking you should not use them on the road but as long as they are aligned ok no-one will care.
Edit: Just reread the thread and realised its a Cally so you got really crap lights. Not a lot you can do really apart from HIDS. Even with the brighter 55w Halogen/xenon bulbs they are still not good. You can't put 100watt halogen in the dipped/fogs because they are too hot for the lenses. Still single filament HIDs are cheaper than H4 for your dipped beam and you can put 100 watt in the main beam, but the standards are not too bad. The 6000k bulbs Micky mentioned look really good.