I use firefox but i have two others including IE (Both old and new version) for website design audits.
That would be Firefox, but I am maybe going back to IE. Much easier to check my sites with a browser everybody use.
everybody's work flow is different. in my case it's 90% flow, 10% work I've been having major issues with IE7, flash driven sites, Pandora.com and the new radar map @ weather.com crash my browser every 57minutes on average when I have those sites open that's why I ditched the FF! Opera is ultra efficient in the RAM dept.
i like IE7 and used for a couple months when it came out but firefox is just quicker, at least on my machine.
I have 1.5GB and it was still cutting into my fun times I think the avg. use was 330MB, it also 'chugged' a lot more IMO...unresponsive script errors all the damn time; more so than my current issue with IE7
this has been discussed a lot! and the answer is the same, i use firefox, it dosen't crash, opens multiple tabs quickly!! lot's of benifits! am not against internet explorere, if only it crashed a bit less, i could have used it