Can you help me install my dell 720 printer with

you can follow these steps:

1.Check if the firewall is blocking any printer services

2.Check what port the printer is using (reenable the bi-directional support) and if it's on online mode

3.Disable all the firewalls

4.Uninstall the printer driver and software

5.Delete any items under the ff keys:
HKLM\System\CurrentControlSet\Control\Print\Environments\Windows NT x86\Drivers\Version-2

HKLM\System\CurrentControlSet\Control\Print\Environments\Windows NT x86\Drivers\Version-3

HKLM\System\CurrentControlSet001\Control\Print\Environments\Windows NT x86\Drivers\Version-2

HKLM\System\CurrentControlSet001\Control\Print\Environments\Windows NT x86\Drivers\Version-3

Optional***
6.Delete any non default items under the ff keys:
Note: ONLY THE NON DEFAULT ITEMS SHOULD BE DELETED
HKLM\System\CurrentControlSet\Control\Print\Monitors
HKLM\System\CurrentControlSet001\Control\Print\Monitors
Default items are as follows:
AppleTalk Printing Devices
BJ Language Monitor
Local Port
PJL Language Monitor
Standard TCP/IP Port
USB Monitor
Windows NT FAx Monitor
*****
7.Delete any items under the ff keys:
HKLM\System\CurrentControlSet\Control\Print\Printers

HKLM\System\CurrentControlSet001\Control\Print\Printers

8.Completely remove drivers by doing the ff: (Option for comm failure because of the upgrade from xp to vista)
Ensure there are no documents in queue.

Disconnect printer’s USB cable.

Click the Start pearl, then click All programs, Printers, Dell xxx (where “xxx” is the printer model number) and then Uninstall. Complete the uninstall utility.

From the start search box type spool and press .

The spool folder located at c:\windows\system32\spool opens.

Rename c:\windows\system32\spool\drivers\w32X86 to c:\windows\system32\spool\drivers\backup.

Rename c:\windows\system32\spool\prtprocs\W32X86 to c:\windows\system32\spool\prtprocs\backup.

9.Restart the computer.

10.Check th services status

Start-Run- Type Services.msc and Click on Open

You will see long list of services

You need to make sure following 4 Services are set to Automatically start

Remote Procedure Call RPC
Remote Procedure Call RPC Locater
LexBce Server
Print Spooler

11.Reinstall the latest printer driver
12. Make sure the driver you downloaded from support.dell.com is compatible with the operating system that you're using, for example windows xp or windows vista.