You'll need to paste text as Shift_JIS format. There's various word processors and such that can do that easily.
If you want to use Japanese extensively I suggest you look at Microsoft's Global IME at
http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=803A623E-C311-4591-A593-B0E24A6F38E8If you only want an occational search in Japanese I suggest you get either NJStar Japanese Word Processor or JWPce.
NJStar:
http://njstar.com/njstar/japanese/ A trial version only, but it goes forever.
JWPce:
http://www.physics.ucla.edu/~grosenth/jwpce.html Completely free but not quite as easy to use as NJStar imo.
Again, be sure to copy and paste as Shift_JIS, not Unicode or EUC_JIS or NEW_JIS.
As a warning you may run into trouble downloading if you don't have Japanese text services enabled. Japanese uses characters that cannot normally be used in filenames under english windows such as | ? / < and >. So if you come across an error like "could not find file <whatever>" or "could not create <whatever>" then you'll have to enable Japansese as the default non-unicode language. It's not a overly common problem since only a few specific characters use them so may not even be an issue, but it is for some files so I mention it.
If you are using Windows XP, you will need to install files for East Asian language and set the Language for non-Unicode programs in "Regional and Language Options" (located in control panel, classic view) to solve those issues.
In Windows 2000 you'll have to install the Japanese IME.