I have always really struggled with Word borders and don't think I've used one since 1998. This is mainly because printers tend not to print quite what you'd expect or something has been set to Letter not A4 and all that stuff from the old days. No doubt things are better now but I can't suggest anything officially Word.
However, two ideas spring to mind (in the absence, presumably of the excellent Serif products?) and they are:
(a) take slices from an image - could be literally anything big enough (ie landscape wider than 3300pixels and deeper than about 2500 pixels for good quality printing). You have your own photos or look for something on morguefile.com or sxc.hu (registration required for the latter but both free) or, I suppose, Google Images (but remember to change options to show only large images). You could find particular colours by using the brilliant Flickr tool on my webtools site - can't remember what it's called but something like Multicolr on this page where you just pick a colour and it finds pics with that shade in. The slices can then be placed on the border of the document as you please.
(b) er, can't remember what (b) was now, oh yes, I know, PowerPoint - you know PowerPoint isn't just for slides, don't you? And you can write letters in PowerPoint just like Word. All you have to do is change the Slide Set-up to A4 or whatever you want. Then design your page the easy way with the usual range of tools. You could easily create a cool background by covering the whole page with a shade, graphic or image even and then putting a white rectangle on top of that. Hey pisto, I mean presto, you've got a very smart-looking template. Add text boxes for whatever you need if others are to use it. In fact, if you put all the design gubbins on the master slide then the kids can't possibly mess up the page anyway.