Help Needed On Decision to Upgrade to a Mac Book Pro

I have an old MacBook from the 2007 era. At the risk of being labelled as a fan boy, I really really like it. I've pimped it out with a 7200rpm drive which I dug very very hard to find in Sim Lim Square, Singapore, and 4 gig of RAM which is about as pimped as it will allow me to. Don't ask me if I'm a Mac or a PC because my straight answer is that I'm more of a Commodore 64/ZX Spectrum and Atari ST520 guy. With its age, it does get me funny looks from the schoolkids doing their homework on much newer machines in the Coffee Bean & Tea Leaf where I spend my days coding and crafting up silly tech ideas.

In a few years time it will be awesome enough to be ironic but, like Georges St Pierre of the MMA, it has seen better days and is causing me problems in the departments of 1) MS Word crashing ever 10 minutes and 2) needing a fan/heatsink thing to sit underneath it. It does do me well, and it can run XCode as well as a bunch of other apps pretty smoothly (so long as the heat sink & fan are used underneath it).

Here's a picture of the beast in action with my 1Tb, Sonic the Hedgehog drive.

So here's what I'm thinking, I'm thinking that the new MacBooks are gonna be wayyyyy better than my current old beast which is almost six years old. That's ancient for Singapore standards.
On that note, I went to the lovely Apple website and found a shiny new entry level MBP for SGD$1688. I don't need the retina display since I use my laptop mainly plugged into an external LCD monitor. So it should be good enough for me.

Then I looked at the specs. Compared to my six year old MacBook there doesn't seem to be much of a difference. Worst still, the hard drive in the newer Mac is a 5400RPM one. Do 7200RPM drives not exist anymore? Here's how they compare:

So my question is: Should I bother upgrading to an entry level MBP and then pimp it out? Or is it not going to be worth the effort and just stick to plodding along with my trusty old MacBook and save up S$5000 for the monster of a 12 core desktop Mac? Apart from aesthetics, what will the benefits be if I change my current MacBook to a new MBP? How much better is the bus speed, hardware, etc in the new MBP? Is it gonna change my life and make me 10 times more productive?

Or should I just spend my money on coffee and more cooling apparatus for my workhorse?