hHere's the advice of my hubby (he's an IT Manager and built our home computers)
Ok, you have several problems here.
Windows 9x( 95, 98) does not truly support memory above 128 MB. To remedy this you have some options:
1. You can attempt to upgrade your Operating system to Windows XP (which is the most stable of all of the home operating systems, DO NOT get Windows ME). However, with your current hardware I would not suggest this.
2. You can call HP and find out what you can do to upgrade your motherboard/pc. You have an HP system chances are it has proprietory hardware, and you will not be able to upgrade it without go thrhough HP first. But this will likely cost a huge amount of money.
3. You can purchase a new machine. All of the major computer manufacturers offewre low end systems for a few hundred dollars. However, you will provbably run into the same issues with upgrading in the future. As hardware will be proprietory.
4. You can purchase a custom built system from a computer show in your area or www.newegg.com.
The advantage here is that you will be able to upgrade your machine, but you won't get the service (tech support) that you would with one of the major manufacturers.