I remove it wheneer I come across it in customers' systems but it's probably best described as half way to being malware. It's a BHO or Browser Helper Object (some may say Browser Hijack Object) and slants your search options to places it wants you to go and phones home where you have been so you probably get ore Spam.
In IE, click the View menu then Toolbars and untick Alot from the list, along with any others you don't need, accepting the offer to disablle them. In ccase anything remains, dowload HijackThis from http://www.trendmicro.com, install and run it and let it fix Alot and anything else it finds. Restart and you're clear of the thing but one of your favourite sites may put it back so keep an eye on the situation.
Firefox has the same facility in its View menu, to turn off unwanted Toolbars.
I used the view on Firefox and I finally deleted the Alot toolbar. It was not listed as Alot, but Navigate toolbar, I just took a chance that, that was the one. Yahoo and Google were listed, so I surmised that had to be the one.