"Using Windows 98 & IE 5.5 SP2"
Until recently, I would have written "stay with IE 5.5 SP2", but that Microsoft code leak changed my stance in that someone found an exploit in how IE 5.5 works with (of all things) a bitmap. This leaves users of pre-6.0 IE browsers at some risk when the exploit is shared all over. At Internet speed, this won't be long.
I will share that I moved up to 6.0 some time ago without issue and for the most part just use Mozilla to dodge the IE bullets.
Bob
Using Windows 98 & IE 5.5 SP2 and am wondering if I should go ahead and install IE 6 SP1. Would appreciate any input and opinions. Thank you.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic