The reason text appears to be 'rough' in FireFox is because it actually adheers to Windows own font anti-aliasing (smoothing) scheme, IE7 doesn't! Microsoft did this for IE7 so it 'looks better' out of the box - completely ignoring Windows own anti-aliasing settings - to fool the non-techie/average joe into thinking IE7 is somehow better simply because the fonts are all nice and smooth.
The FireFox team however used their heads... FireFox actually actually uses Windows own anti-aliasing settings, which is a good idea. If someone has a low-end/older PC they will probably have anti-aliasing turned off in Windows to give their CPU a break, so why would they want it
on in their browser?
This is yet again another cheap 'trick' by Microsoft to fool the uninitiated masses. Most people with XP, by default, don't have full anti-aliasing (ClearType) on so IE, with its own font anti-aliasing, will look better than FireFox straight out of the box.
Its akin to Microsoft and their IE 'Now with tabbed browsing' boast... FireFox has been doing this for ages (not sure about any other browsers, I haven't used them), unfortunately there's still an extremely large percentage of people who don't even realise other browsers exist. Even Amiga's had browsers with tabbed browsing over 10 years ago!!
Personally I would never, ever go back to using IE... its far too vunerable to 'drive-by downloads'. Its FireFox all the way for me now, especially with the No-Script plugin which I consider an absolute essential. No-Script blocks all JavaScript, Java and Flash until you specifically allow it for each domain. While this may sound like a pain, you only have to allow the content once if you trust the site... everything else gets plain old HTML so absolutely nothing, without exception, can be run in your browser without your explicit permission... It even blocks adverts coming from domains other than the one your allowing... so it can even speeds up browsing! (For example if you've just allowed the domain 'myspace.com' and MySpace's adverts are being served from 'someadvertserver.com' then the adverts won't be allowed (unless they are just plain old GIFs or JPEGs), thus speeding up your browsing)...
Anyways... Preaching over now!
