Let's step back a minute.
Are you:
a) trying to run the query and have it display to the user (in the browser) as an Excel spreadsheet/file?
or
b) trying to run the query and then save it to the server's file system as an .xls file (then can then be opened on the server by Excel/OpenOffice/whatever or downloaded)?
I had assumed a)... but now it's sounding more like b)?
If it is a), then, no, what the server has installed (MS Office/OpenOffice/WordPerfect Office) makes no difference... as the handling of the file is actually on the client's machine. They would need MS Office... or, at least the plug-in or control that understands the Excel mimetype.
If it's b), then, yes, obviously whatever system you're trying to view the Excel file on (in this case, it sounds like it's your server??? *see below) would need something that understands an .xls.
The trick with b), however, is writting the .xls. It's not a simple file type... and you'd have to understand a great deal about the file format to actually be able to write one using ColdFusion (if it's even possible). Usually it's better to save yourself the headache and write your data out as a .csv file, which is a simple file type (comma-separated values... about as simple as one could get). Excel can easily import a .csv... though in some cases it isn't as easy as simply double-clicking the file and letting it load... Excel may need a pointer or two to figure out what data types it's looking at.
That being said, * you really shouldn't have OpenOffice running on your server unless it's absolutely necessary. Nothing gobbles up system resources faster than office applications (okay... so maybe Photoshop gobbles them up faster). And you really don't want that sort of drain on the same box that's running a web server (particularly if it's, in turn, running ColdFusion). Better to copy the file (whether it's .xls or .csv) to a local system (not a server) and opening it there.
Just my $0.02,
-Carl