I know whats wrong with both issues because Ive had and dealt with them both.
However, if you could make a reply with your complete system info I could probably track down conflicts for you. Not having that information, I can offer you this:
RAM: Youve got the wrong type of memory. Some motherboards handle mixed ram better than others and it sounds like yours doesnt. Make sure that youve got ram with the right bus frequency and type. capacity and pin # arent the only defining factors. the ram you have in your comp now likely wouldnt have a sticker telling you exactly what type of ram it is (pc3200, for example) so its likely that you bought a stick of ram thinking it was of the same type, but wasnt. I would advise you to bring your old stick with you when you buy the new one and make sure you are buying a match. When you computer makes the beep when you turn it on and it doesnt boot, thats definately a ram conflict. The solution is to make sure your new ram is the EXACT same type as the old.
GFX Card: This is a problem I have had all too often, especially before I could afford to purchase a card that came in a box with printed requirements and profiles. The problem is one of 3 things, the first two being the most likely but hardest to fix. The last being a no-brainer.
1)I had this exact same warning code appear when I bought my BFGTech GeForce 6800 GT OC. It ships in an overclocked state and required 2 molex power connectors to run. I found out that my power supply was maxed out and couldnt power the card. When I installed a power supply with higher wattage, the computer booted fine. You might have to get a new power supply.
2)The second possibility is more common and occurs with pci devices often. Some mobo manufacturers like to have a single pci port that is specialized for a communications card like a faxmodem or nic. Other times they are design for a specialty card designed for use with the motherboard and software bundle that usually includes the card. It should look like an oddly shaped, stunted-looking modem. In years past, manufacturers didnt indicate which pci slot was the specialty one, but usually nowadays they are a different color from the others and are usually the last slot. HOWEVER, some pci slots are arranged to support differnt bus speeds. If your card isnt compatible, well it wont run. My advice in this case is to simply try the card in another pci slot. You might have to try a few times. If youve got a card in a slot that you know is working, remove it and try the gfx card in its place. If it works, youll know which slot is the dead one. I think this is the most likely of the 3 scenarios.
3)Your drivers could be out of date, incompatible or broken. This is the simplest option since it requires you to do nothing more than uninstall and install software instead of messing with hardware, but since it is the easiest to fix its probably not the right solution (thats how it tends to be). But you can still try it. Get online and do windows update. Get everything that comes up. Then surf to your motherboard manufacturer's website and download their drivers. Next, head on over to the GFX card manufacturer website and download their drivers. Its a nVidia card, so the download area can be a bit confusing. Dont stress when you see those 3 little boxes on the download page. Just click on "Graphics Driver," then "GeForce and TNT2," because this includes your software line, then "Windows XP" for your operating system. Hit "GO!" and your download should start. Remember not to install any of these before you UNINSTALL the old drivers. Also, you might have to do this several times before it will work. Just keep at it and you should succeed, provided this is the solution to your problem. I would recommend trying this option first as it is the simplest and least likely due to its simplicity.
I hope these suggestions help you. Like I said, not being there and not knowing your hardware profile means that the options I offered could be way off, but I tried to cover every option you could take. The one that I didnt offer initially is the most disappointing; your hardware could have shipped broken. The card could be bad or your pci slot could be cooked. Its not so nice to consider, but if all else fails this possibility will appear the most likely aside from a freak failure somewhere else.
Let me know if any of this helps.