So, my fan makes lots of noise when I turn my PC on and continues to do so until switched off. I can fix it by shutting down my PC as soon as I get to the desktop and then restarting once the fan has completely stopped. This really annoying to have to do every time so I need a new fan.

http://www.okobe.co.uk/ws/product/Acer+Aspire+X3200+Desktop+Computer+AMD+Athlon+64+X2+5000+2.6GHz+3GB+RAM+DDR2+SDRAM+320GB+HDD+with+Microsoft+Windows+Vista+Home+Basic/1000016319?ref=1q4bs is a link to my PC, except mine came with 4GB of RAM, not 3.

Can anyone recommend me a good fan that will fit? I'm in the UK, so Newegg might be out. I don't know if they ship overseas since I've never tried them before.

What size fan do you need...for brands scythe sflex or yate loon

what you described is sometimes caused by dust buildup on the fan or poor lubrication.

maybe you just need to clean your old fan or use something like sewing machine lubricant.

probably a seized fan by the sounds of it. All the oil sounds like it's gone so now the fan is rubbing against itself while it spins.
You can always try NCIX. They may or may not ship overseas, but it's worth trying out.

If I'm thinking of the right thing, case fans DO NOT use oil. They use bearings. Sleeve bearings are in the cheapest fans, and they fail regularly because friction introduces flaws that eventually ruin the function of the bearing. Better fans use ball bearings. These generally never fail (in the lifetime of the computer).

Pay a few bucks more for a better fan. I like ones that are labeled "stealth" fans because they are engineered to either move more CFM with less RPMs and/or they just make less noise cutting the air. Cheaper fans make a lot of noise just from how the blades cut the air as they spin.