A few of things I've noticed:
In the error message you sill have 'the no topics met...' which is irrelevant as it never bothered to search. Also you spelt length as 'lenght' :P
"Note: Minimum keyword lenght that can be searched is 4 characters" should only be displayed if the input is below the 5 char min imo
Can you make it so that if you change forum category your search criteria is kept in the text box? Annoying as hell atm as it goes as the page is updated.
It's not the length of the entire search which needs to be above 4 chars, it is every word (as you know) - AMD, CPU, SKT, 939, 754, DDR, FAN, VIA, etc can't be used
:? :? :?
Removed the warning about minimum word size, and put it in the input screen where you specify search keywords. Check it out.
Cannot maintain the input keywords from screen to screen if you change category, since the input has not yet been registered into the system. Also if I cookie the input, and then it is shown thereafter in the search input box, then it will interfere with the username box, since both cannot be set.