There are a number of possibilities for this problem. I would check the following:
1 - Tie rods from the front suspension strut to the anti-roll bar, if one or both of these are worn you will get a knocking noise coming from the area low down in front of the gear stick.
2 - Drivers side drive shaft support bearing, if this is worn you will get a rumbling noise while driving.
3 - Wheel bearing, same symptoms as above. (but unlikeley, they last for years)
4 - Clutch release bearing, if worn tends to be quiter when clutch depressed.Possible leyshaft problem in the gearbox.
Difficult to say exactly without details of the noise, rumbling, knocking etc.