eh?? I have an Asrock P4i65G Prescott P4 board next to me with an ECP parallel port on it. That's a 2006 vintage.
You are correct, it looks like that board was released in March of 2006, but it really doesn't help the case that parallel ports aren't outdated when it was a legacy support board even when it was released. LGA775 had been out for 18 months at the time and the AGP slot just speaks for itself.
(and blow me, it still works with the original processor I bought for it as well, a 2.66GHz P4)
You might want to grab a Kill-a-Watt or similar and test your power consumption. Prescotts weren't exactly known for being efficient in the first place and a lot has changed in the CPU world since then. Anandtech's CPU Benchmark Database has the Pentium 4 HT 660 which is a year newer, a full gigahertz faster, and has twice the L2 as yours. When you factor for the clock difference, a 10 watt Celeron is pretty much just as fast in single threaded loads and since everything has multiple cores these days multithreaded performance will be a whole different world.
With how cheaply you can get CPU power these days anything from the P4 era or older can be hard to justify keeping around both for power/heat reasons (particularly notable on Prescott chips) and performance. If you actually use that day-to-day I guarantee that a dual core chip would be practically a religious experience by now, not to mention if your electric costs are anything you care about it very well could save you enough to cover a lot of the upgrade price over the course of a few years.
I'm not saying you need really awesome gear, just that even cheap hardware these days is hugely better than that. Until a few months ago I was running on a Phenom X6 1045 that cost me $90 brand new when I bought it over two years prior. It still did just fine for me day-to-day and I felt no need to upgrade. Yeah it's six cores, but an end-of-life chip that was sub-$100 when bought is by no means a monster build.
We reached the point where for most day-to-day tasks you generally don't need any more performance some time ago, but that doesn't mean there's no reason to replace old hardware. I do contract IT work for a bunch of customers and at this point my line is Core 2 Duo. Anything older gets replaced when possible (made a lot easier by XP being EoLed with no security updates), anything newer gets upgraded to 4+GB of RAM and a strong recommendation of a SSD. Even a first-gen C2D is pretty hard to tell from a Core i7 in most desktop tasks if it has enough RAM and the SSD.