MX518 is the way to go!
Since the MX500 is very very hard to get these days and the MX518 is available, I have to also vote for the MX518 for the same reasons. I have two MX518s (one to replace the MX500 on my present system and the other for my new system early next year) waiting to be used when my MX500 (4.5 years old) bites the dust.
Here's a link and a couple quotes (not from the link):
http://www.esreality.com/?a=longpost&id=1265679&page=1
"Ok, I got it installed and setup to the recommended 3/11 sensitivity which means set the sensitivity in the mouse control panel at notch number 3 running on the PS/2 port and after that went to windows control panel, mouse, click on properties and then advanced, set the sample rate to 200 instead of the default 100 and this thing is like night and day from the G5.
It's impossible to make skip and it just feels so precise, for example I use a program called StrokeIt that gives me mouse gestures for all programs, you draw a gesture and assign it to a command, with the G5 it failed to recognize commands half the time, now it's just dead on everytime.
It's hard to explain, it just feels WAY more presize than the lazer mouse and the wheel click doesn misfire half the time and scroll instead."
"Yeah same here, I got the G5 and I guess I was still rusty from not having played since 2k4 so I didn't notice, and everyone was complaining about the bad aiming before the patch, but it realy is night and day from the G5.
I got 2 and probably going to get a few more next month, I think it will be a long time if ever when the lazer mice gets better, I used the 510 and 518 and they do break kinda fast for me, longest was about 6 months, always the wire that breaks right where it leaves the mouse, funny how fragile all mice are now, my dad has a MS ball mouse that he had since back when 33mhz was a super fast pc and it still works, have to clean the ball and rollers once in a while but it just keeps on ticking.
And what good is like 6000dpi if the mouse starts flicking around randomly when you move it to fast. Funny these lazor mice are getting rave reviews by "gaming sites" and none mentions that you get tons of negative acceleration."
