How many times can you upload XP onto different PCs?

If it's a retail version, up to three. If it's an OEM version, then just once.

btw, upload means sending data to someone across some kind of connection. You probably mean "install"

Depends. If you have it on different PCs at the same time, you'll technically need a Multi-PC license (you could just do it with a single license, even though it would be illegal, not many people care). If you mean just putting it on a new computer, where you won't be using the old one, you should be fine.

the correct verb is "install" not "upload"

i've done it countless times, i've got an enterprise version which means you just enter the serial number during installation. it doesn't need to be activated, which is the methodology used by microsoft to limit your installations

10 times is the max amount of times u can install winxp with a disk to you computer