Slow net with HD connected

This is kind of confusing.

Ive just recieved my 11" Ultimate air today im loving it so far but im finding when i connect my external HD which ive freshly formatted the web browsing on the machine slows really bad often waiting a few seconds for links to open.

As soon as i disconnect the drive it works fine.Does anyone have any idea as to what the problem could be?

Only thing ive got on the drive is my iphoto/itunes librarys and they are empty at the minute.Ive also installed Macfuse NTFS-3G as i originally had the drive fomatted as an NTFS filesystem but ive now re-formatted as extended journaled.

Any help would be appreciated.

Thanks

Actually scrap that..it just seems very slow full stop

Nothing else is connected to the network.

Running a Wireless N Netgear DGN2000 router

Any ideas guys?

Thanks