Unfortunately, step 1, I cannot get a real good handle on the specs of what I've got!! The nVidia website has them, but qualifies it for OEM cards "Specs may vary by OEM". And Dell does not publish the detail card specs as built! The card is supposed to have HDMI, according to nvidia, but yet I see no HDMI connector slot. There's 28 listed specs on the nvidia site and it's not always clear which ones are choice-driven (HDMI, dual-DVI, etc.) or critical (Min System Power Requirements). The main goal is to be sure it is compatible with the rest of the PC. I don't know for sure which items point to compatibility issues, or relate to robustness or are just optional features.
For example, Memory Interface Width claims to be 256-bit on mine, but most others I see are 128-bit. Do I care? Bus Support says existing card is PCI-E 2.0, but other cards I've seen 2.1 or 3.0. Does that mean it won't fit or is that a more modern good thing? Memory Interface for existing is GDDR3. Does that preclude GDDR5 for me? Texture Fill Rate is 37.8 on mine and 28.8 on a candidate card. again, do I care? probably not, but I don't know. Width is single-slot on mine, and dual-width on another. Probably okay I think because other slots are unused. On and on and on...
It would be nice if Dell had an upgrade path to overhaul 3+ year old systems for the casual end user who is not proficient in hardware details, but they would prefer I just buy a new computer, I'm sure!
Thanks for the toms link, but seems more attuned to gamer cards. I couldn't find any filter or detailed search capability. Newegg has good comparison and advanced filtering capabilities that I have been using, but now I have to understand the results!!!
I checked out the ATI 5450 mentioned above (thanks, Bob) but it says it requires 400W PSU. Perhaps they are being conservative in that spec, but there are a few geforce cards that state 350W min which seems wiser. The 5450 also stated PCI Express 2.1 x16 and I don't know what that refers to compared to my existing 2.0.