Speedfan and MSI K8N NEO-FSR

[Hamman]

Hi everybody! I'm new to this great forum, so I hope that you will be patient with me.
I've just built a (budget) system consisting of:

Mobo: MSI K8N NEO-FSR s754
CPU: Sempron 2600+ s754 with stock cooler
Memory: 512mb Kingston 400mhz CL3
Harddrive: Samsung Spinpoint 80gb
VGA-card: Sapphire 9600pro 128mb
Crappy case and PSU (But the PSU is quite silent actually)

I decided to try CPU-burn, and after 1h 20min, my temps are (according to Speedfan):
Temp1: 46
Temp2: 52
Temp3: 42
HD0: 42
This is with the stock cooler@3000RPM
What does the different temps mean? I understand that HD0 is my HDD, but what about the others? Anybody have an idea?
Are these good temps, or way to high? It might be helpful to know that I do not have any form of case fans installed.
Thanks in advance.

[jojo4u]

I decided to try CPU-burn, and after 1h 20min, my temps are (according to Speedfan):

Have a look at "charts" in Speedfan the one with the biggest variance is you CPU. You should not care about temps as long as you PC is stable

[Hamman]

Thanks for the tips on the charts!
Regarding temps: If I can't be worried about the temps of my computer, what then should I be worried about?
Seriously, It's nice to know if your PC runs cool or hot, especially when you're planning to buy better/quieter cooling.