Improved File Sharing For Windows XP

Could anyone tell me if there is an improved way of file sharing for Windows XP other than the standard printer and file sharing option?

I’m sharing an office space with 4 other people who are freelancers and I would like to limit the sharing of my files between my computer and 1 other. There is no server here, we’re all connected by a wireless switch.

Is there also a way to improve the speed of transferring files between 2 PC’s?

Thanks in advance 😉