Ok so I've been trying to connect to the internet on my other PC using the same connection as this one. For ages it says "Aquiring IP address" then it says it has no or limited connectivity. I've tried inputting the IP ect manually but then it says its connected but doesn't actually do anything at all. Can anyone help please?

It would be helpful to know how you are trying to connect your PC to the internet.
If you are using broadband, are you going through an ethernet port or a USB port?
Are you connecting directly through the modem or are you using a router?
Generally, when you are connecting through an ethernet card to the internet hooked directly through either a modem or a router, you will want to make sure that your ethernet card is being recognized. Right click on My Computer, click on Properties, Hardware tab, Device Manager button and then check the ethernet device to see that it is recognized.
Finally, if you are using XP you may have a winsock corruption. Use Google and find Winsockfix.exe or WinsockXPfix.exe. Run one of them, reboot and see if you can make your connection - of course this is all premised on the assumption you are using a broadband modem.

Ok i am on broadband, I have tried connecting using ethernet and USB but niether work. the Winsockfix program didn't fix the problem either. I can't understand this!!

Broadband as in DSL or cable?

Most cable ISP's will only allow one MAC address at a time so you would need to reboot the modem to change PC.

To have both PC at the same time you would need a router.

Yes, it is very puzzling. I am presuming that you are not using any type of firewall, even the one that comes with XP. I have seen this happen when an ethernet card goes bad or is not seated properly, but since you've connected through a USB port that would seem to rule that out.

After booting up your computer, bring up a command prompt and type ipconfig without any parameters at the DOS prompt. This should give you the address it has acquired from your ISP through your modem. Then, type ipconfig /release and then ipconfig /renew. If it times out, but the modem light shows a connection, my guess is that you have something amiss with the ethernet card.

If it does give you an address type something like ping www.google.com and see how long it takes and if there is any packet losses. If there are packet losses, your signal to the modem is bad.

Some folks change the windows registry parameters to speed up their machine. Some games played online at one time did this. There are tools on dslreports that can set the parameters back to their windows default and/or modify them.

Without knowing a lot of specifics, I have thrown out some suggestions, most of which you've probably tried. But, keep coming back to let us know what you've tried and what the outcome was.

You can also use a hub to set up a dual connection.

You may need to manually setup the network connection.

I've got it working now, I just reset the modem, thanks for your help guys!!!