My external hard(250)gb drive takes ages (10 mins) to mount.And after that it runs quite slowly.

I, dual boot Ubuntu with windows,but in windows it runs quite smoothly.
SHOULD I REFORMAT IT????
What could the problem be??

Configuration:
Intel P4 3.02 ghz
Ram:800mb
Running Ubuntu Maverick and Windows XP SP3
Hard Drive Capacity:160gb