By default, Windows XP Start menu has got some delay to respond your cursor. Here is a simple registry tweak to remove (or reduce) the delay.
- Click "Start"
- Choose "Run"
- Type "regedit" without the quotes
- Go to the registry location "HKEY_CURRENT_USER\Control Panel\Desktop" and find "MenuShowDelay". (If it doesn't exist, create new with this value name and String data type.)
- Open it and change value data to "0" instead of default value "400". (You can choose 100 if you don't want it to respond too fast)
- Reboot your PC
Note: You should keep a backup of your registry before doing any changes.