Have Microsoft Windows XP.....purchased HP Officejet J5780 all in

if your printer is already, click file -> print, then do you hear the voice from printer. if not, your printer is not boot.
and you said your preview is blank. you not load the page with content. I guess you don't have the right to print it.
by the way, if you forgot the office password, visit this site to know how office password recovery

Software issue. Contact MS since HP will do nada for you since it is not a printer problem. Maybe your excel program is not really compatible with Win 7. Check it out.

Use http://www.magicaljellybean.com/keyfinder/ to find the serial number. As for the corrupt Excel program, you may need to determine what exactly is the problem there.

Go to Start, All Programs, Microsoft Office and see if Excel is listed. If it is, then click on it to launch it. Does it open? If so, then go to where your excel spreadsheets are saved to (e.g. My Documents) then right click an Excel spreadsheet & click on "Open With". Select Choose Program. Select the Microsoft Excel. If Excel is not listed, click the browse button and browse to C:\Program Files\Microsoft Office\Office12. Click the Always use the selected program to open this type of file checkbox. Click OK

Make certain all HP Drivers and Firmware are up to date. HP has diagnostic software free.

Go to the following site and install the updates from HP

http://h10025.www1.hp.com/ewfrf/wc/softwareList?os=228&lc=en&dlc=en&cc=us&product=3441026&lang=en

go to www.hp.com and download a new driver of your scaner for xp

The reson is because you have not installed the latest printer drivers. try updating printer drivers or contact you printer manufacturer for further assitance

FAX    RINGS BUT WILL NOT ANSWER 

I also had this problem, through trial and error I found that if you go into File, Page setup in excel then the Page tab, make sure the print quality is set to 600 dpi. Once I did that it printed correctly.

maybe there is a blank page that you did not notice in your document, most of the time it happens in excel or spreadsheet. It also happens if you have a default printer then setting it in a different printer without checking your documents if there is any changes.