This app used regularly helps:
http://www.danish-shareware.dk/soft/emptemp/ You will need to do a Find for all Temp, Tmp, Cache folders and add them one by one to the folders cleaned. Also make sure in the settings, that Recycle Bin & Temporary Internet Folders are being cleaned.
She can also speed up the cache by doing a few things:
1. the size may be set too small: in control panel / internet options / Temporary Internet Files / Settings / Check for newer versions of stored pages / select: every visit to the page(if she's on a slow dialup this may actually slow things down, but if she doesn't do this, she'll just be viewing older versions of pages) AND further down she can increase a bit the cache size
2. this app, besides cleaning the cache, fixes a bug in IE's cache size index:
http://www.enigmaticsoftware.com/cachesentry/index.html run it manually once in a while, when it wants to reside in the system tray(bottom right) just double-click it, it will freeze for a few seconds while it scans the cache, and select on the bottom right: Kill the sentry.(you want as few programs running in the system tray-- they use up the processor & memory, slowing down your system...
Note, if anyone wishes a diagnosis in this area, with suggestions on what to stop from automatically running(& how to stop it, hard to do sometimes), just run this app-- hijackthis:
http://www.spywareinfo.com/~merijn/ , start a new thread, and i will take a look at it-- btw it will also list all spy & junk ware running.
speaking of all the malware that slows your system down:
run both adaware & spybot(they each catch different stuff), they get stuff that gets past firewalls & antivirus:
http://www.lavasoftusa.com/software/adaware/
http://www.safer-networking.org/en/download/ update them first, before running, then in Settings enable Deep scans, all drives & folders to be checked, scan priority mode(so it runs faster), etc.
Here are some apps that in tandem prevent a lot of this beneath the radar stuff:
https://netfiles.uiuc.edu/ehowes/www/main.htm this one in particular you'll need to manually update once a week, but it adds all known bad & spam sites mentioned by all security sites & software makers-- very thorough:
https://netfiles.uiuc.edu/ehowes/www/main.htm
and:
http://www.javacoolsoftware.com/spywareguard.html
May also be time for defrag/scandisk/rearrange the programs in order used--
http://mvps.org/PracticallyNerded/SoftMain.htm it utilizes winME's scandisk & defrag instead... they're 32bit as opposed to win98's 16bit Dos versions, plus they're 100% efficient in stopping all running processes, so that they run 10 times faster than win98 version!!!
speaking of win98-- no need to throw it out(until 64bit chips AND software compiled for them become prevalent): i've replaced a lot of its innards with ones from WinMe & winXP(does void the Eula, but performace is great)... if any tweakers are interested, I'll provide links & resources on how to do it-- same for removing a lot of unnecessary modules from any MS OS version--
And as far as speeding up, be aware that all OS come by default with things disabled(to prevent issues with older, slower equipment): win98(danger here: must have fairly new memory, processor, & hard disks: otherwise you can damage the system... usually post 2001 will work)-- 32bit / concurrent disk/memory access, winxp dma/udma, intel chips need the intel chip accelerator to enable some stuff, etc., etc.
There's a lot of stuff that should be tweaked in all OS(and in the Bios!!!)-- for instance in XP, file indexing, cache settings, its native firewall, etc.
If interested, i can provide several links & resources for that.
good luck.