i suppose that if you are in business, then as kalmsg suggests, then paying the extra, might be worth it. however if not in business, then it may be better to think again
several years ago, i was on dial up, and i also wondered if from time to time, maybe my speed then was somewhat comparable to what it is now, and i also am on 512 kbps. of course, from time to time, the system got mighty slow, and i out that down to the operating system getting full of rubbish, and when peak times, also slowed things down
there are some websites, that test your download speed (for both local, and international data), and give a comparison, for the average of those sites.
i really have no idea, how it all works, but one reason why you probably think that there is not much difference in your download speed could be, that there could be a lot more advertising linked to the sites that you visit - and all of the advertising needs to be downloaded. i did some tests on this, and by cutting out the advertising (ie block images, java script etc), then the amount of data downloaded can be decreased by about 75%
before giving up on 512kbps, maybe you should try and reinstall windows (if you are using windows), but prior to reinstalling windows, properly clean the hard disk (a good program to use - try "dariks nuke and boot").
despite the limitations, just try the offbyone browser - that might be a bit quicker, for some of the sites that you look at
i use puppy linux, for most of my internet use - this operating system does not get bothered by trojans etc etc - and a clean reinstall, only takes minutes. indeed, the whole operating system can run in ram, and when switched of, nothing goes onto the hard drive - pretty safe
