How much space do the registries take in the computer?

My computer has so many useless registries but I know I shouldn't touch them.  Just wondering how much space they take up.  Do they take up a lot of storage space in a computer?
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No, not usually, but you can clean themup with regclean
I usually run it a couple of times (may not get all the first time)
save the undo.reg files for a while, will be way less than 1mb
make sure everything runs good for a couple of months, and then you can delete the undo.reg files
another utility called "System Mechanic" which have some advanced registry cleaning features (including CLSID). you may try that as well.

free download available at
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look at the size of user.dat, system.dat, user.da0 and
system.da0 (.da0 are backup copies). You should also add
the size of rb*.cab (these are backups including the registry)

Unless you have a really small hard drive, these files
should be a non-issue from a space standpoint, for best
performance you should trim them anyways by getting rid of orphans etc, see previous comments.
registry usually only a couple or five megs in size.....
myplaceAuthor Commented:
Stevenlewis, your link didn't work for me somehow.  Do the programs have instructions of making backup files?

So the registry files don't take up a lot of space but they affect the performance of my computer?

"look at the size of user.dat, system.dat, user.da0 and
system.da0 (.da0 are backup copies). You should also add
the size of rb*.cab (these are backups including the registry)"

I don't understand this.
The files I listed are the registry and backups.
In win 98 the active registry consists of user.dat and
User.dat contains user settings eg. stuff like
what desktop wallpaper you're using, colors,
how folder are to be displayed, etc.
Systems.dat contain information about your system
eg stuff like what programs are installed, file
associations, hardware info, etc.
The system keeps a backup copy in the x.da0 files
You got another copy i the .1st files. This copy is static since it's taken when you install windows 98.
When you (or the system at boot time) run scanreg /backup, a file is created containing system files including the registry. By default, the system will keep five copies around.

When you install a program, usually entries are added to the registry. Unistall is supposed to cleanup, but is
often incomplete.
The hardware section of registry is never pruned,
it will remember every device ever installed.

A lot of entries in the registry are related. For example,
if you have an extension .xxx there should be another
entry say xxxFile containing open information eg what program
the system is to run when you double click on it.

Over time, entries that are supposed to be connected to
other entries become or are created without the required
linked files. These orphans and other unnecessary information may be tracked down and removed be utility
programs such as the ones mentioned in other comments.

If you take a look at the file sizes involved, you will
see that all in all, we are not talking about very much
space here, but like I said in my previous comment
for best performance you want prune it anyway.
Maybe a bit more information than you asked for... :-)    

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myplaceAuthor Commented:
Thanks.  So before I clean them up, I should make a backup of these files?
Well, to be safe and know where you're at,
go to run, type command, and type scanreg /backup.
Run your cleanup program and verify that
the system still seems to behave well.
If there is a problem and you want to undo,
restart the sytem in msdos mode type scanreg/restore
and select the file that has the timestamp corresponding to when you took your backup, and you'll
get back to where you were.
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