Hi Moon - Defraggler is advertised to work on all Windows operating systems, including 64-bit. Here is an extract from the download page:

[quote:3362lqjw]Runs on Microsoft Windows 7, Vista, XP and 2000. Including both 32-bit and 64-bit versions.[/quote:3362lqjw]

You can see that for yourself [url=http://www.piriform.com/defraggler/download:3362lqjw]HERE.[/url:3362lqjw] Scroll down and look under 'System Requirements'.

So no, you should not run into any problems.

How often one should run defrag software depends largely on the amount of use the machine gets. More use = more frequent defrags.

If you are installing/uninstalling software often, moving files around often, adding /deleting a lot of data, and generally consider yourself to be a heavy user...then I would suggest once a month.

If you are a light user; mostly internet browsing and emails...then probably twice a year would be fine.

For the 'average' user (if there is such a thing) I would recommend somewhere in between....defrag the drive around every 2 - 3 months.

BTW: The built-in disk defgamenter which comes with Windows 7 is reputed to be very good, a distinct improvement on previous models. Here is a link to a tip on how to schedule regular disk defragmentation using the native software: viewtopic.php?f=26&t=965&p=5752#p5752

One thing to bear in mind Moon; before running any defrag software it is always wise to thoroughly cleanup the hard drive first. Use a program like [url=http://www.piriform.com/ccleaner:3362lqjw]CCleaner[/url:3362lqjw] (also from Piriform) to assist. Use your browser's cleanup options to delete history and temp files. Also run the Windows native 'Disk Cleanup' software. There's not much point in defragmenting files which are only going to be deleted later anyway, plus leaving them in place will only serve to lengthen the defrag process.

HTH,
Cheers....Jim

Hey Moon - You are most welcome.

Best to choose and use just the one defragger and not two different ones (e.g. Defraggler and Windows Disk Defrag). They all use a slightly different standard (method) and, although it really can't do any harm, it will take a lot longer as one will undo some of what the other has already done and will also negate any benefit derived. (hope that makes sense )

Cheers....Jim