Upgrade to improve speed?

The 4600 is original AGP DDR 1 slow netburst Pentium4.   Netburst was abandoned by INTEL as was AGP.   Newer systems use DDR2  DDR3  DDR4 etc.    A good transition machine would be Optiplex GX620 Tower.  Getting one with Dual Core Pentium D means you can go all the way to windows 10.

https://www.amazon.com/Dell-Computer-processor-Interlaced-Intregrated/dp/B00EK0AFO2

You would be able to copy data files from your old drive easily.

Newer models Like the GX745 755 760 780 are even faster but they can be more expensive.  They also do not have IDE interface like the GX620 has.   The unit below is not overtly expensive and is a huge speed increase from the 4600.

https://www.amazon.com/Dell-Optiplex-780-Performance-Professional/dp/B00JJYN2EE

kennyg33,

There is really nothing else you can do to make the computer faster. You could try upgrading the processor. It may not improve the computer speed that much. 

Thanks.  Was hoping that I could upgrade the hard drive to solid state.

Thanks.