Your best bet is to hope that a port of OpenOffice.org sufficiently 'lite' or optimised to run well on the 770 will come out.
Trust me on this: Microsoft will *never ever ever ever ever* release a version of Office for Linux. No way Jose. No. Definitely not. (they've gone on the record saying so as I recall)
Just discovered Thinkfree Office Online (www.thinkfree.com). You could try this as a way of opening the file...not sure if it will work with 770, as I do not have one to test, but if it does please please please post back, cause this might just be the thing that convinces me to buy one
Good thinkning, but that definitely won't work at the moment - it loads a Java applet to run, which of course requires a Java VM, which doesn't *yet* exist on the 770.
Basically, 'watch this space'
I did manage to install Abiword on my 770 just fine and that supposedly is compatibe with Word docs, but I've not tried opening one yet - I expect it'll work fine except for documents that use some of the trickier features in Word (tables, autoformatting, headers/footers with dynamic info in them etc etc).
(they've gone on the record saying so as I recall)