What is the bottleneck in this system?

Well if the ram is uneven (2GBx1GB) that can slow it down

You should probably upgrade to 2x 2GB RAM. There would probably be a speed increase.

Better graphics card if you wanted to do demanding 3D work. (memory rating only needs to be high for HD gaming. storing the textures in the memory) This GPU is a home theatre GPU for blue ray and other HD content + basic gaming. i.e steam games.

SSD in Raid 0 might make loading the system faster and will help when copying lots of data.

DDR3 ram would be faster, but get the fastest DDR2 & also non-ecc ram is a little faster. EEC is error correcting ram mainly used in servers. You get a slight overhead with this process. (but you knew this already right?)

I would could change the DVD combo drive for a blue ray player / burner and combine it with a nice big HD screen.

If you do want an increase, you would want an SSD, more RAM, and possibly more video memory.

The only thing like one of the others is the ram Make it even like 4 or even 8 if it can take it. if not leave at 4gigs. The only other thing if the SCSI connection is raid capable. And if you can find another 3-4 more you can make a raid 5 for easier data recovery. Since Raid 5 if one disk fails the other ones can take the load until you get a replacement one. And from there raid 5 can rebuild the black disk in there once you get the replacement in there. The Sata disk is okay as well. I've used a couple of times IDE and SCSI over here when I had my adaptec in one of my older machines.

The video card will run most games passibly, but not at high FPS. You might consider replacing the video card and putting in more RAM.

Still a lot of compatibility issues with SCSI, pull both drives and install identical 1TB SATA drives in RAID 0 if you want the best possible speed, RAID 1 if you want redundancy.

RAM. You're powering two Xeon processors, both of which are drawing from those 3GB of RAM. I would go for at least 2GB/CPU, preferably 4GB/CPU. Upgrade the RAM and this system will fly.

A few notes:

1. The graphics card. I'm 14, and I have a better graphics card than that system in my own. That thing isn't going to take you far. If you plan to do extensive 3D work or play any games, you need an upgrade. (The 5770 is an excellent choice.)

2. The RAM pairings. Mismatched RAM isn't optimal for system performance. Upgrade to a 2x2GB configuration, and you'll notice that you'll get a speed increase disproportionately large to adding just an extra gigabyte of RAM.

3. There ARE some unavoidable bottlenecks. No matter how fast your RAID 0 SSD setup is, it'll still be pretty damn slow. Accept that, and compensate by upgrading the hardware you can. Get an SSD. Also, upgrade your internet connection (I hear FiOS is good): no matter how fast your NIC is, it won't affect performance. Internet connection is the biggest bottleneck there is. You'll get the same performance out of a USB connection.

You guys are forgetting that his CPU, even though are Xeons, they are from MANY years ago. Pretty much within the same family as Pentium4.

His setup is pretty balanced, imho.

Why are so many people assuming this is for gaming?

This computer is a workstation, so you should assume it should be used more for that sort of task.

First, it is an old setup, so it will all be bottlenecking a little.

The RAM is only DDR2, which while good, a lot would benefit from at least 4GB DDR3 if the computer is being used in the way it should, for video editing and graphics work.

Secondly, since the CPUs are fairly old, I would assume that the motherboard is too, and that the chipset probably isn't up to modern standards.

The HDDs will be bottle necking too.

If you have the money, it might be worth investing in something that is not necessarily a workstation, but something such as a Sandybridge i5, with about 8GB of DDR3 @ at least 1333Mhz and a modern chipset.

This would then allow you to add a 120GB RAID0 SSD array with the 2+ built in Sata6Gb ports for an additional £200/$280.

Obviously, I don't know you situation, and this is only a suggestion, but if you want more information, feel free to get back to me, and my contact details are on the website listed on my profile.