virtualbox.org

is the i5-3320M a reasonable cpu to run 3-4 vms simultaneously, or should i give more money

Depends on what the guests are going to be doing and what OS the guests are.

The guests will mostly be linux and windows.

It will be nice if I would be able to e.g. watch videos with a reasonable ease inside the vms.

I will use them to test how well different applications work together within a specific os. Running 3-4 vms concurrently will also be nice for making presentations to customers.

Running videos in a guest is about the most intensive thing that can be done in a guest. The processor you list has 2 cores and if you intend to run 4 guests like this you should have as many cores+1 for the host. I would also have an ample amount of memory, but even then it may not play as well as you would like.

The i5-3320M system will take 16GB RAM max. Also this cpu has Hyper-Threading.

Still you don't think I'll be able to watch youtube videos within the VMs?

Should i definitely get a QM cpu? The i7-3720QM would be my next option money wise

I didn't mention hyper-threading for a reason. Not good in any virtual environment.

i5 isn't bad just get one with 5 or 6 cores. if it is available. VT-d and EPT will really help too and of course VT-x goes without saying.

Thx, i didn't know that about Hyper-Threading

The processors I'm thinking about are M(mobile). Can get only up to 4 cores afaik! The thing is I have to do VM work while I'm away.

4 cores it is then. just give the guests 1 core each and keep an eye on it. Hopefully you will not be running video in all of the guests at the same time.

Does it matter if I use Linux as host OS? Will that make it easier to run more than one VM on the same core in the case of a dual core cpu?

What matters is the resources available (e.g. RAM, disk space, CPU cores), not the host OS.