Can anybody help me getting antivirusetc formy HTC S710

Http://www.htc.com/www/supportdownloadlist.aspx?p_id=8&act=sd&cat=all

The above link is to HTC website. You can install a rom update for your phone and see if it helps.

The battery problem you are experiencing is not a virus.
It is probably a worn out battery. Something that is important to remember with these smartphones is that they are very electronically intensive. In other words, as your battery gets older it just doesn't have the power to keep your phone running or will die out faster as time goes on.
You can try letting it discharge all the way, charge it to full and use it till it is all the way discharged. and charge it full again.
do this 3-4 times and see if it gets any life back, if not buy a new battery.

Here is a link for downloading windows mobile device software for your desktop.
For Vista Only:
http://www.microsoft.com/windowsmobile/en-us/help/synchronize/device-center-download.mspx
For XP
http://www.microsoft.com/windowsmobile/en-us/help/synchronize/activesync-download.mspx

Good Luck