I tether to my HTC EVO all the time with my A500. My EVO is rooted though, and it is running Cyanogen Mod 7, so tethering is super simple with it. You just go to the wireless settings on the phone and activate the tethering and portable hotspot, and then go to the tethering settings and get the access code.
Then just enter the code into the Acer when it tries to establish a connection with the phone and it should link right up. You will only have to do this once, after that it will link automatically if the A500 senses the activated phone hotspot.
Tethering can drain the phones battery, so if i am tethering for an extended period I just use the wall or car charger.