I run a Beretta 92FS Vertec Inox in USPSA Production and IDPA SSP. Same as the regular Beretta 92FS just a slightly slimmer grip, dovetailed front sight, and stainless steel. Only mods are a fiber optic front sight and some trigger work. Most guns for USPSA production division and IDPA that is all the work you'll need to be competitive.

The Beretta's aren't very popular these days in competition, but I get along with them. It got me 3rd overall at the USPSA Space City Challenge this weekend. The overwhelming favorite these days for USPSA Production division and IDPA SSP is the Glock 34 or 17. I've never cared for the grip angle or flat side panels but they are great guns. The other popular choice for Production division and SSP is the M&P. The Springfield XD and CZ's will work in Production but in their stock form will have to be in ESP for IDPA. A 1911 single stack will be good for USPSA Single Stack division and IDPA CDP division. There are a number of good choices out there. Pick the one you like and learn to shoot it.
By far the best forum for information on competitive practical shooting of any type is at
http://www.brianenos.com/forums/index.php?act=idx It mainly focuses on USPSA but the information there can be applied to both disciplines.