OPPS....IM LATE BUT I GOT THE SOLUTION FOR THIS PROB AND ITS VERY VERY SIMPLE TRUST ME...here it goes..... read on.....:

1) Connect ur Nokia N900 with ur usb cable first and SELECT [PC SUIT MODE] from N900.

2) Now u need to activate the N900 PC SUIT MODE ON UR PC....SO Right click on MY COMPUTER > select MANAGE > select DEVICE MANAGER > (on the right hand side screen) select NOKIA N900 under WIRELESS COMMUNICATION DEVICE > OPEN IT....AND select ENABLE

NOW ITS DONE... it will install the required pc drivers and aft a few mins ur PC SUIT WILL WORK 1000%

pls leave ur comments and ratings for my post... as i fpound the solution myself... i didnt google.

thanks and NOKIA N900 ROCKS!!!