skype stopped working properly on linux for many users when microsoft took over (surprise!). I personally have had the same problem as you.... if you call someone skype crashes. this isnt the fault of ubuntu, its the fault of MS b/c they are the ones who are maintaining skype now. I still dont know how to fix this or what to do myself...
Also regarding speed... what exactly is slow on ubuntu? Ill venture a guess that internet browsing is painfully slow. In that case you need to install google chrome... Firefox is just slow on linux thats how it is.
I'm beginning to think that the issue may be with your OS and not your BIOS. You mentioned that you are currently running Mint. I don't know that much about Mint but do they have a version with just a single CPU kernel? If so, then such a kernel would report the correct number of cores, but only use one. This is an unlikely and wild conjecture on my part as I can't imagine any modern distro that would compile a uniprocessor kernel.
The best thing for you to do at this point is to run a LiveDVD/USB instance of Xubuntu 12.04 and post back the results of lshw. This will bypass everything on your HDD which might be limiting your cores. Don't use your old copy of Ubuntu. Instead, download the stable version of Xubuntu 12.04 by torrent. I prefer to use torrent downloads if available. Not only is this less taxing on the Xubuntu server/mirror ecosystem, but torrents tend to have less corruption due to their robust dynamic error checking while downloading. The torrent site can be found here.
Thread moved to Recurring Discussions.
Entirely dependent on you hardware specs and what you want to do with your computer. Try them all from the install disk and see what works ...
Granted, Chromium is faster, but only marginally so. I run both on some older machines, and difference is not significant. It most certainly should not require 4 to 5 minutes to launch FF. That points to a deeper problem....Ill venture a guess that internet browsing is painfully slow. In that case you need to install google chrome... Firefox is just slow on linux thats how it is.
A moment ago, I suggested running lshw in a LiveDVD/USB session. In this same session, please also try launching FF and timing the delay between clicking the icon and launching the app.
ibjsb4 has already helped you determine that /proc/cpuinfo shows four cores (which is what s/b expected), so it may be that your system is already using all four cores and is just misreporting two. If so, then you can ignore the readings from lshw as far as cores are concerned.
On a practical note, if your system is now acceptably responsive, there may be little further to be gained beating this dead horse, which is a further reason for ignoring the core readings.
Never had a problem with Skype on my three completely different machines. Install it from the repos, not manually.