I've recently installed a Java grid software ,for volunteer computing, on WindowsXP.
I noticed I got 90-95% cpu usage, because of it, despite its priority was 'low', the lowest in Win

Is it ok?

As far as I understood, such programs should use CPU as little as possible, only in idle periods.

I can't say specifically about your particular application, partly because you didn't say what it is, but the one that I run will use all of the CPU available, but it runs at the lowest possible priority. That means that any other task that the computer wants to perform will take precedence over this application. I don't notice any decrease in response on my Linux system when I'm running this software. (Folding at Home)

There is a distributed project engine called BOINC that many projects have used to create their distributed computing software. I believe that BOINC works a lot like Folding at Home on Linux.

Folding at Home on Windows only works when there is a screensaver running so that is completely different than the way it works on Linux. Not that that has anything to do with your question.

Mine is D20L@home by sengent.

When I noticed that CPU usage,I was using Bittorrent, and its down rate was unusually slow, so,I thought it was for D2OL's client.
After having close D2OL, rate began to increase

Maybe it's too heavy being made in Java?Or ,by using idle periods like disk access, which is frequent in Bittorrent, it inexorably slows I/O bound apps?Or it's just a case?

thanks for your attention!

Does the program use bandwidth (internet) when it is operating by itself? If so, it is likely to continue doing so when other programs are running too.

No, it doesn't

The whole point is to use spare CPU cycles. When the computer would otherwise be doing nothing, yes - CPU utilization will be pegged at or near 100%. Even when you are working, CPU utilization will stay at 100%. Properly implemented, its impact on your computer's performance should be minimal.

By the time SETI@Home switched to BOINC, I had processed over 15,000 units and was listed in the top 0.1% of all SETI@Home participants worldwide. If your grid client software is as efficient and well behaved as SETI@Home, don't be concerned over high CPU utilization. CPUs are not like engines. Properly cooled, running at 100% utilization doesn't make them "wear out" faster.

Does most Grid Computing software use no bandwidth?

Actually, all of them do. However, it is normally not very much data. It has to download a work unit, process it, then upload the results and get the next work unit. Most projects have fairly small work units and extremely modest bandwidth requirements. There are exceptions. There is a global climate modeling project whose data acquisition requirements are enormous.

Actually, Folding can be run as a service in XP and Win2K.

Never mind guys , it was just a case, there have been two days during which a torrent I was downloading slowed down, but not for D2OL.