[Solved] Real world (not OC) noticable differences of p4 @2.4 & 3.4

Hi everyone! Seem like this is the place to ask, but this is my first post, so be gentle!

I am wondering whether it will be worth say, $45 to $55 to get a 3.4GHz P4 with HT either (512k/800FSB or 1mb/800FSB) when I already have the SL7E8 2.4 ghz 1mb/533FSB (no hyper-threading) or will the difference be negligible for all practical purposes?

BUILD & USAGE CONTEXT:

This will be on an 478 socket mobo from ASUS model p4p800-e deluxe with 2 gb ddr400 ram (2xgb in dual channel config) with MSI Geforce fx 5900xt AGP video card and 600 watt coolmax PSU. (stock cooling)

Almost always will be having MULTIPLE browser windows open and another word/office type app or media player, often with photoshop cs2 editing of large or higher res pictures. Not for gaming, but lots of streaming and playback of video, maybe some editing, but not much.

MAIN QUESTION:

How much real-world time (ie - WHOLE seconds) or minutes of difference would we be talking about between options of my chip vs 3.4 with 512/800 and HT, and my chip vs 3.4 with 1mb/800 and HT? How much affect on performance does each variable (Ghz, cache size, FSB, HT) have in this scenario? The differnces between instantaneous and super-instantaneous are not of concern, but a noticeable lack or improvement in useability for say, media decoding and encoding, or rendering with Photoshop or multi-tasking IS.

Note: I AM saving up for new "enthusiast-end" stuff, so please, no responses that tell me not to put $ into old tech, etc. I DO realize that I could get better from low-budget newer tech but that means a new mobo et al as well, and I already have this to work with which doesn't suck. I just want to max it out within reason considering noticeable performance for real world situations.

*afterthought*: could I overclock anything and acheive the same results or would that be ridiculously troublesome?

Thanks, in advance!

Do you mean then this 5-10 sec difference would be due to the difference in Hyperthreading tech as opposed to Ghz/clockspeed? Actually that could be significant amount if that is multiplied by a number of executions, particularly in photoshop. What if I could pick up a 3.0 or 3.2 HT cpu for 20-25 bucks? I think my wallet could definitely handle that at this point. And thanks - this is the info I was looking for in terms of real time info.

Is there any popular software that does use SSE3? I've only seen this term in reference to vid cards and what they were using... There is a possiblility that the agp card might be updated at some point... I'm not even sure what the 5900xt uses though.