Using network drive for backup

> Trying to use a IOMEGA USB drive on another network maching DELL XPS to
> backup from laptop DELL Inspiron
> .
> I get a ID and PW request (all network settings are for shared)
>
> The network share could not be accessed for the following reason:
> No mapping between account names and security IDs was done.
> (0x80070534)"
>
>
> The laptop is Vista Home and the network main machine is Vista business.
> The drive is mapped on the laptop, but not pw protected.
>
> Can I use this USB on the other machine as a backup destination. If not
> is
> there a MS Vista compatable backup software. I am backin up photos and
> itunes data mainly and want regular incremental backups.
>
>