Compaq Presario C500 is a windows vista base model where the drivers for windows XP and Windows Vista is available on HP support site. If you plan on upgrading to windows 7, here I listed the drivers you will need. There are many Compaq Presario c500 series available (a very long list) but all of them using the same device drivers except for wireless.
All C500 series use Intel 940/943/945 Graphic. Basically you just need to install vista drivers for the graphic drivers in windows 7.
Intel 940/943/945 Video Driver
Version 126.96.36.1992, 15MB
This driver only for 32-bit. Even reported work, if you failed to install the driver, this guide may help you to install the conexant driver in windows 7.
Conexant Audio Driver
Version 188.8.131.52 A, 5.47MB
This driver is for LAN port, which let you connect to the internet or network using wired connection. There are 2 version reported work.
Realtek Network Controller (NIC)
Version 6.103.0123.2007 A, 4.6MB Download
Version 6.101.1124.2006 B, 4.0MB Download
Here i list the applicable wireless driver for this model. Included both vista drivers which work for windows 7, and windows 7 drivers released by HP. If You wireless already worked after windows 7 installation, you don;t need to install this driver.
Broadcom 4321/ 43xx Wireless Driver
Version: 5.00 B, 3.79MB (Vista) Download
version 184.108.40.206, 21MB (win7) Download
Intel Wireless WiFi Link 4965 Intel PRO/Wireless 3945 Network Connection Intel PRO/Wireless 2915 Network Connection Intel PRO/Wireless 2200 Network Connection
Version 13.4, 15MB Download (latest)
Version 7.00B Download (vista)
Other drivers are available on HP ftp server, but not listed in the download section. Some of the original drivers work with windows 7 and there are also latest version which available for windows 7.
Conexant Modem Drivers
Version: 7.61.00.00 A, 28MB
HP Quick Launch Buttons
Synaptics TouchPad Driver
Version:220.127.116.11 A, 34.76M