http://www.cisco.com/en/US/products/hw/switches/ps607/products_tech_note09186a00800c4546.shtml

1. Log into your switch, and enter the privileged EXEC mode by entering enable plus the enable password.
2. Enter clear config all to reset the entire system.

You don't need to reload the switch because processing the command wipes the switch. If you've set a boot option, you need to change that option using the set boot command.

If your switch runs Cisco IOS, it maintains a running configuration file and a startup configuration file, both of which you need to clear. Follow these steps:

1. Log into your switch, and enter the privileged EXEC mode by entering enable plus the enable password.
2. Enter write erase, which erases the NVRAM file system and removes all files. At the prompt, confirm that you want to erase all files.
3. Enter reload, and enter no when prompted to save the configuration. (Otherwise, the switch will reload the current running configuration.)
4. Confirm that you want to reload the switch, and your switch configuration is almost clean.

It's almost clean, but not quite. Most people forget to clear any VLAN information they've created for their switches. Depending on the hardware version of your switch and the software version of your OS, the command for this varies.

show vlan

dir flash:

dir cat4000_flash:

dir const_nvram:

delete flash:vlan.dat

erase cat4000_flash:

reload

http://www.cisco.com/en/US/products/hw/switches/ps708/products_tech_note09186a00801347e2.shtml

http://code.google.com/p/tftpgui/

Connect to the switch's serial console port.

Configure the networking so the switch can communicate to a TFTP server.

Start by entering EXEC mode:

enable

Make room for the new firmware image, if necessary:

dir bootflash:

delete bootflash:<old-image-file-name>

squeeze bootflash:

Download the file to the switch:

copy tftp: bootflash:

Address or name of remote host []? <ip-addr-of-tftp-server>
Source filename []? <new-image-file-name> 
Destination filename [flash]? <new-image-file-name>

Determine the current boot statement that you want to remove:

show bootvar

show config

To remove the boot system flash statement, enter into configuration terminal mode:

configure terminal

no boot system flash bootflash:<old-image-file-name>

<ctrl-z)

write memory

Set the new boot statement:

configure terminal

boot system flash bootflash:<new-image-file-name>

<ctrl-z)

write memory

Verify and reboot the switch:

show bootvar

reload

Verify the new system image:

show version

http://www.cisco.com/en/US/products/hw/routers/ps133/products_tech_note09186a008022493f.shtml

Verify this in the output:

Configuration register is 0x2102