Why not check Tomshardware CPU charts? http://www.tomshardware.com/ch...3DMark06-CPU,370.html
For 3dmark CPU:
Pentium E2140 = 1393
AMD Athlon 64 x2 (Brisbane) 4000 = 1557 (sorry couldn't find the 4200 Brisbane on the chart).
But there are many factors that make the whole PC experience different such as:
- Amount of RAM 1GB - 2GB should be enough
- Hard disk size and speed - checkout http://www.storagereview.com/Testbed4Compare.sr
- Graphics card (I'm assuming you're using the onboard graphics). This whether the 945G or 6150 is better I have no idea.
These are somewhat dated machines. If you're into playing games then you'll need to get a recent graphics card.
I'm on a Windsor 3800+ running at 2.2GHz with an nVidia 9600GT and am pretty happy with it for some light gaming.
This is just my perspective...