Dear Bizi,
I am afraid i may have discouraged you unnecessarily before.

My doubts as to the effectiveness of the java tool were in regards to overall benchmarking (measuring pure computational speed). Thinking about it you are more likely concerned with issues such as slowness in booting, shutting down, opening programs - Word, Excel, etc)... or internet speed.
Computers do not inherently become slow
because they are old. Computers can become slower in time due to usage - stuff installed/uninstalled etc can produce a variety of issues, such as:
-- disk fragmentation (very common)
-- too many services running (comes from installation of lots of programs)
-- change in antivirus (the service takes more CPU time than the old one)
-- low disk space => fragmented pagefile
-- dirty registry (many superfluous entries)
i am not sure that your provider's tester
does this kind of checking (i was unable to read the page

) but there is no problem with it being a Java program insofar as effectiveness for this.
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Similarly a Java app can measure connection speed accurately, if that is your concern, i.e.....
if the slowness is specific to internet-related activity...
-- opening a new page
-- refreshing a page
-- pressing submit to a post or even just
-- hitting thanks and waiting for it to "show up"
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Chances are that either way the problem can be resolved. If internet speed is the problem, then you should certainly make sure you are getting the speed you are paying for.
For the rest, one just needs to find the issue(s)... and act accordingly, eg. removing/disabling unused components/services, cleaning up a hard drive (if it has many "bad" areas," replacing it)... etc.
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I'd say let Jeff have a look at that tool, and see if it corresponds to your needs. if so, have him install Java and proceed.
Ball is in your court. you sounded tired of this after the hassles you described, so i figure you'll take a break at least. just know you have my support if you need it - holler if you have other questions/issues.
~ waves ~