Any good ways to upgrade this PC?

Nothing that would be worth it. That computer is six years old. You can only upgrade the CPU to a faster Pentium 4, which definitely isn't worth it. No PCIe slots or even an AGP slot, so a video card is pointless. You could put a bigger hard drive in it, but honestly, what is the point? That computer is worth less than $100. Save your money for a better one.