According to this that I looked up...
Resident Evil needs a fair bit of CPU. Even paired with a GeForce GTX 285, it averaged just ~21FPS with that CPU. It seems to make use of more cores, more cache, more frequency, any and all of them. A Core 2 Quad Q6600 is matched by a Core 2 Duo E8400, so dual core CPUs seem to be able to play, but one with low cache/low clock speed probably won't cut it very well, and your CPU is pretty low on both. Look at the difference between a Core 2 Duo E6600 and the Core 2 Duo E8400. They only have 2MB L2 cache and 600MHz separating them (you can argue ~700MHz effective from Wolfdale's clock for clock advantage), yet the difference is pretty big. I think even if you overclock, you'll only get so much in that game.
Originally Posted by edalbkrad
If you think of it. your E2160 is just like splitting your P4 660 in half.
From single core 3.6 ghz to dual core 1.8 ghz
1.8 + 1.8 = 3.6
That's more like a sidegrade not upgrade.
The problem is the cpu not gpu, better overclock the E2160 to 2.5 ghz
My nephew has the same HD4650 but he can run RE5 at high settings with his E5700 3.0 ghz.
A Pentium Dual-core is a Pentium in name only. It's really a Core 2 Duo architecture, so it's not to be compared with splitting the Pentium 4 in half (that'd be true with a Pentium D at that clock speed). The Pentium Dual-core E2160 will be a bit faster, PLUS run cooler and save alot of power versus that Pentium 4. The OP did make quite an upgrade. It's just still slower compared to what that specific game needs.
Of course, the GPU could indeed be holding it back some too. If your nephew's getting playable performance, here's his CPU compared to the OP's.
I wager alot of the difference (over half) comes down to the clock speed, and the cache is the rest. If the OP can overclock that CPU a bit (2.7GHz or so), it should cover alot of the difference, so there's still alot of potential left. I overclocked one from 1.8GHz to 2.7GHz no problem on a basic $50 Gigabyte G31 motherboard, and it also went to 3.0GHz easily as well, but I left it at 2.7GHz since it was at stock cooling at the time. I'm not sure it'll make night/day difference in this game though, going on those benchmarks.