Having used toasters for a very long time, I have developed a basic toaster test using the Elder Scrolls series as benchmarks.
Here are the tiers and benchmarks. Obviously, this only refers to actual windows PCs, and not anything else.
<Probably can't run much outside of DOS games
Tier 0: Dinosaurs (???)
< Can Run Morrowind
Tier 1: Toasters (At least 256 or 512 MB of ram, either a good cpu with integrated graphics or a not as good cpu with an ancient graphics card)
<Can Run Oblivion at all
Tier 2: Toaster Ovens (Minimum 1 Gig of Ram, probably 2, along with previous specs)
<Can Run Oblivion with min 720p resolution and graphics that aren't all set to low
Tier 3: Microwave (2 GB Ram, plus either a old crappy GPU or just good integrated graphics + cpu)
<Can play Skyrim on 1080 with graphics set to high or better
Tier 4: Decent PC (almost certainly has a dedicated graphics card, decent cpu, 4GB or more of RAM)
Tier 4 is the baseline where you can expect to be able to play most games you'd want to play without running into too many issues, although as games continue to be more demanding, Tier 4 becomes less of a baseline for what you can call a decent PC.
OP's PC I would guess is somewhere in the Tier 2 to 3 range, so you are probably safe with a lot of games made before 2010.