Hey, have we all forgotten that the latest Opera (10.01) is in our repos? It's under testing.
In Linux it's always best to use a package created for your distro. So run Gslapt and see if what you want is available in a VectorLinux package. You may need to have the testing repo enabled because new versions are in testing first.
And here I want to disagree with standard advice given in this forum, namely, not to have testing enabled. You don't want testing enabled if you're going to Mark All Upgrades and then execute an update of everything for which an update is available. In that case, yes, be sure you don't have testing enabled when you run Update to find what's available. Similarly, if you have the autoupdate notification enabled and you routinely tell it to update whatever it tells you is available.
But if you're not going to do a universal upgrade, I think you *should* have testing enabled. All new packages go in testing first and they may linger in there for quite a while. Updates for Opera, Firefox, and SeaMonkey are in testing first. Do you really want to stick with the older version until the new version wends its way out of testing? Browsers are often updated because of security issues.
New versions of other programs often have desirable features added or bugs fixed. If you don't have texting enabled, you may not know the programs are available in Vector packages for months.
Note that when you do a Mark All Upgrades in Gslapt and then View menu, Marked, you can see where in the repo the package is. Just scroll down package by package and look at the bottom panel under Latest Available Version and if something is in testing, remember that means there might be issues that haven't yet been found. So yes, you are a bit of a beta tester when you use packages from testing, but Linux users are beta testers all the time because many programs never get to a 1.0 release (meaning it's considered stable and "done"). If you don't want a package, just uncheck it in Gslapt.
I would rather go through the bother of seeing what repo available upgrades are in than miss out on the latest versions of certain programs such as browsers. I usually pass on upgrades still in testing, but it depends on the program. Also, using programs that are in testing is a great service to VectorLinux because unless people *use* the programs, we'll never know if there are problems in the packages that should be fixed. So maybe you won't want to install packages in testing on your production machine, but fpr anything else it's very rare that a program in testing will trash your system unless you do a system-wide upgrade that includes packages in testing. Need I mention "backups"? Nothing will trash your system if you can restore it from a good backup.
To get back to the original situation, don't use DEB packages. Even if you convert them, they may not put files in the same place as VectorLinux does. Opera has long offered packages for Slackware--if there isn't a package in our repo, which is a much better place to get it. We don't live in the Ubuntu world here.
If you do download a DEB, find it with Midnight Commander, highlight the file, and hit F2. One of the options is to convert the DEB to a Slackware TGZ. Give that a try. Once it's converted, you'll need to su to root and run installpkg nameofconverted.tgz.