Is this memory configuration safe?

I have just received my 2x2GB Crucial Ballistix Tracers PC2-6400 KIT. I dont wanna put away my old GEIL memory so I decided to throw it in there with the two Tracers.

Okay so heres the deal.

I first tried out the Tracers and booted up. Defaults were 800mhz @ 1.8 5-5-5-18 ..however when I use EasyTune it shows the voltage @ 1.9

So I guess they are working.

Then I threw in the other 2x1GB GEIL Kit. Seems scary having them side by side like that. Its like they would touch one another as both have heatspreaders.

Anyways, my GEIL kit defaults at 800mhz @ 1.8v 5-5-5-18. Just like the Tracers were showing up.

Ok now I have a total of 6GB of memory. All running the same timings of 5-5-5-18 800mhz supposedly at 1.8v but EasyTune5 says 1.9.

Which is one of my biggest concerns. Even with just the GEIL on it rates it a 1.9.

In other words ...

--Is running my GEIL and Tracer together alright? Again at 1.8v err 1.9v reported by EasyTune5. 5-5-5-18

--Is it normal for them to be spaced out so closely like this? They just barely touch one another. I do have a 120mm Drive bay fan facing them (Antec 1200 case ) Its on high. Actually there are two fans on that Drive Bay all facing towards the memory and no HDD in between them LOL.

2x2GB Crucial Ballistix Tracers PC2-6400 KIT should run at 2.0v.
It's okay for the Geil also. It won't hurt anything.
You should increase the voltage of the memory to +0.2v.

CPU-Z only shows nominal voltage. It always shows 1.8v.
Bump it up to 2.0v.

If you mix memory, it will use (on auto) the slowest timings.
You can tighten up the timings and run memtest86+ and check for errors, overclocking the memory essentially.

Run the memory at 800 MHZ with the 4-4-4-12 timings.
That's the best you can get at stock.
Test for errors with memtest86+.