welcome to the forum.
Without knowing exactly what motherboard you have makes it kind of hard to tell you if it is upgradable to to the use of a PCIe card. But I would venture that you can't. You stated that you have USB 1 in your system and that suggests that you have an older motherboard and does not even have a PCIe slot which is totally different than a PCI slot that you probably have. Here is a link to a utillity that will tell you exactly what the motherboard is that you have and you can post that info back in a bit and will look it up and tell you which upgrades are available for you in the video department.
Now you should be able to use a PCI USB2.0 insert card that will allow you to upgrade that part. You can't change USB1 to USB2 but the USB2 is backward compatable ....so your USB1 hardware can be used with it....but it will not increase the speed if that is what you are trying to do. 1.1 will remain the same no mater which plug you put it in.
Hope that helps