With Passmark:
2.8ghz P4 (stock) = score of 741
3.4ghz 2600k (stock) = score of 10,082
Should give you a idea of what kinda ballpark your in.
The Pentium 4 had low IPC (kinda like bulldozer today vs intel),
but high clock speeds (2.8ghz was high back then).
You know the E-350 and E-450 APU's that AMD has a 18watts for CPU+IGP....
they re both rated higher than a P4 @ 2.8ghz in Passmark.
As bad as that might sound... the graphic card is the main problem.... its... really slow.
To obtain a Passmark score, the program uses a suite of GPU, CPU, Memory, SSD/HDD tests to calculate the score. I'm 100% certain a 2600k's iGPU would destroy a 7300LE, as would the E-350 and E-450's APU (CPU/GPU).
Looking at a Passmark score from years ago on a Pentium 4 and comparing it to a score run on a rig 6-7 years later is not a valid way to compare results.
The most accurate way would be to use identical rigs, at least as close as possible. A more valid comparison would be on an LGA775 platform in which a Q9550 could be swapped with the P4 whilst the RAM,HDD, and GPU remained the same. THIS would provide an accurate spectrum of results to compare.
Nonetheless, the P4 IS most definitely about 15-20% the speed of a 2600k @ stock, perhaps closer to 40% in single threaded apps, but even so... it is a severely aging CPU. I'm not sure which socket P4 you're running but if it's LGA775, you could easily upgrade to a cheap Q6600 and be set for a couple years, and easily see a performance gain of 500%.
With all that said, the 7300LE is a horrible GPU, even for a P4 rig. I would suggest grabbing a 5750 or 5770 if you're running on a PCI-Express chipset, as it would provide the most bang for your buck these days, even if you aren't able to harness it's full capabilities with your CPU, you will be able to once you swap your CPU in the future. It's pointless to spend $50 on a GPU when in the future if you swap your CPU or platform entirely, you'll be bottlenecked by the GPU to an extent that you were nearly with the original P4. Get something worthwhile that will last. An HD5770 or 5750 will allow you to play a few DX11 games on low detail, and to at least enjoy gaming much more than you are now. A 5770 can be found open box or used for $75.
Good luck