I have heard a bit about it - has alot to do with all the "built in" so called accelerators in IE8 from my understanding.
Since they are on dialup, first off make sure you tweak the Dial Up Network connector - DUN
http://forums.speedguide.net/showthr...ght=56k+tweakS
^ is a good place to start.
Also read here:
http://forums.majorgeeks.com/showthread.php?t=188887
Also try a different browser - and tweak the settings to not display pictures/animations (flash anims, etc). This will cut down on the bandwidth needs.
Last thing - and I know for our elders its hard enough - but if they could afford it - look into satellite internet. Out in the boonies its the best there is - the latency is high (but that only affects online gaming so isn't likely to be an issue for them) - download speed is comparible to DSL. It is weather affected though.