why cant i install a wireless mouse,do i have to uninstall wired mouse fist??

No you don't have to install the wired mouse.

Do you have all the hardware installed?
Maybe you just need to update the drivers.

Hi. Unplug your old mouse before you start your computer(the round PS/2 plug) and replace it with the new sending unit.The new unit should come with a USB to PS/2 connector adapter.Use the adapter and plug the sending unit were the old mouse was(PS/2 connector).Start your computer and let the OS come up completely.Then turn on your wireless mouse. You should be all set.I received one for Christmas and it took me two trys to figure it out.Word of advice(go to control panel under mouse and reduce the mouse speed because wireless really flys.Good Luck and enjoy!

No, you do not need to uninstall the wired mouse for installing the wireless mouse. Just ensure that the driver as well as the connecting medium is well connected.

There is no such thing as "uninstalling a wired mouse." Usually a wireless mouse is plug-n-play but some require driver installation. Does it come with any driver/software CD?

Remove the wired mouse first. Some wireless mouses require the installation of their software before your PC can recognize the mouse.