HELP!! WHERE CAN I SAVE?? e1705

*Disclaimer: Apparently I write long winded posts. If you are kind enough to read through and help me price a computer, I am truly grateful. I got a possible $500 to save, as well as the piece of mind in knowing that I didn’t waste any money! Thanks for helping this obsessive geek!*

I'm a semi computer nerd but I'm not really a gamer. I have always known enough about computers to know that, as a non-gamer, most every option is a waste of money. about 5 years ago I purchased a refurb. Dell dimension 2300 (1.8Ghz celron and a whopping 256mb Ram) for $350 after shipping. It was more than enough all the way through college.

Today, I have needs beyond word-processing and web-browsing so help a cheap SOB out and tell me what I do/don't need.

Basically, I will be multi-tasking most of the time. I run a database program which imports data into files as large as 500mb. On my dimension 2300, this program is a complete CPU hog. My cpu is often running at 100%.

When using firefox, I sometimes find myself with 2 or 3 windows open; each with 5-10 tabs running at the same time and the process uses approx. 125,000K mem (on my page file I guess?)

I would like to "future proof" my laptop ONLY if the price is right.

My upgrade specific questions:

Where is my most likely bottleneck?

Should I get the CPU with the higher FSB (667Mhz vs. 533Mhz)?
(if I get the higher FSB I gotta get DDR2, right?)
Total cost of upgrade (CPU and Memory) = $150

Which Video Card!?!?! I am clueless here. I will be getting the UXGA upgrade and will run at 1920 x 1200.
My two options are
Ati Raedon x1400 for + 90
or the Nvida 7900GS + 270
My nerd side is having a wet dream over the Nvida. My wallet just needs to know why would I need it, isnt the ATI just fine?
Cost ATI->Nvida = $180

Is 1GB of memory enough (I am assuming it is plenty, but not sure)? What good would more mem do?
Cost of 1GB->2GB upgrade = $175

Better to go for higher HDD speed... right?
Cost 5400RPM->7200RPM - $80

Perhaps the biggest savings might be had if I just knew when or how to buy a Dell? Two weeks ago they were offering 35% off this compy at 1999+. Now a paltry 20%. Anyone got the secret to maximizing dell sales?

Thanks so much for any help!! Any comments welcome!!