external hdd not working properly

I have a fujitsu storagebird 35ev840 1tb HDD which was working fine when i fisrt had it using windows vista. i have about 80gb stored on it. since i put windows 7 on it has never worked properly and appears to have a driver issue. it is no longer showing when i click on my computer but if i go to devices and printers it appears with a yellow triangle by it as i write this but sometimes when i plug it in the triangle is not there and the device will work incredibly slow if at all. I tested on my mates laptop running XP and again it did not show up in my computer but i was able to remove an audiobook from it and put it back on it very slowly and i can also play files that was stored on it. I could reaaly do with getting this working properly as my laptop needs a complete new install of windows on it but first i want to swap about 180gb of data to my HDD.
Any help and i would be very grateful
cheers