Windows 7: Slow transfer speeds, WHY?

Hi there all,

I am running a pretty well high end piece of hard ware, probably more than i need. But there is something that is mind boggling me...
Please explain, why is it when im moving files over a network im getting ridiculous silly slow speeds?

I have an i5 with 5xHD in it, 2 x 500GB for mirror/raid 1, then i have 3 x 3TB, one of those 3TB is partitioned to 2TB and 1TB.
AND
I have an i7 with 3xHD, 2 x 1TB and 1 X 2TB.
(i have listed both my pc system specs below if you want to take a look after reading my problem)

Now why is it that im getting REALLY SLOW transfer speeds from pc to pc over a network?
Im moving large GB files and small ones and my transfers speeds are all different and cant put my finger on it why. I have went through and read across many, many forums like this one, and many others and I cannot still find out a good reason why!
anything i am reading no-one really knows, they are just saying things like, just try this and try that.
Im running a small business and im not going to be mucking around with system settings, off people's hit and miss theories, although i have tried a couple already and thats about how far im willing to go.

However, same file sizes and same HD, are giving me different transfer rates, im transferring files between my i5 & i7, both are windows 7 professional 64bit.
I can not list any examples at all because its all different, but my average transfer rate is from 1.5mb to 30mb, but 90% of the time its 2mb to 10mb.

I have ALL BRAND NEW HARDWARE 2 weeks old, not even. So i know its not my hard drives and its not my hardware, (mobo, cpu, ram and so on) I am leaning more towards the O.S. Windows 7 Pro 64bit, as there are like a billion forum topics and threads about it.

So can someone actually help me and finding out an answer?
Just cannot understand why this not happen when running XP Pro x86 compared to the newer Windows 7 Pro 64bit.
I have installed a 3rd party program "TeraCopy" but still same transfer rate.

I wish i could call someone over the phone as there is way too many variables to be written and i dont think there would be enough room in here to write everything that i have tried and done.
Inshort i have tried the following...
Changing NIC settings
Unticked "Remote Differential Compression" on both pc's
installed 3rd party software "TeraCopy"
Also i was thinking of uninstalling the intel software thats running my NIC settings
- Not willing to go any further until i know 100% exactly where the problem lies....

BTW
FROM i7 to i5
Transferring the files to a USB 2.0 Ext. HD took me 7mins to move a 60GB File, it was taking me 7.5 hrs over the network, @2mb.
FROM i7 to i5
I have also transferred a 20GB file through network 2 days ago, took me roughly 10mins.
FROM i7 to i5
I transferred 1TB folder over network 4 days ago took me about 2hrs.



Never had these issues with XP, running smaller hard ware.

Thank you

Troy

SYSTEM SPECIFICATIONS

i5 PC - bought this 3-4 months before my i7
CPU

i5-3470 intel

Mobo

GA-Z77X-UD3

Memory

Kingston 1 x 8GB 1333MHz

Hard Drive

Seagate SATA 2 x 500GB 16MB Cache & Toshiba SATA 3 x 3TB 64MB Cache

GPU - if its necessary

Asus GT630

PSU - if its necessary

Cooler master 550W

i7 PC
CPU

i7-3820 intel

Mobo

GA-X79-UP4

Memory

Corsair 2 x 8GB (total 16gb) 2133MHz

Hard Drive

Seagate SATA 2 x 1TB 64MB Cache & (i forget make Toshiba/Seagate SATA 1 x 2TB 64MB Cache

GPU - if its necessary

Gigabyte GTX660Ti

PSU - if its necessary

Cooler master 750W

What kind of LAN setup do you have? Router/switch, etc.

Lmao thats one thing i forgot to mention, sorry.

i have a modem-router from telstra/bigpond CG31000 CABLE.

my i7 is connected via ethernet cable, my other pc i5 is wireless 300Mbs
I have made up my own work group name so all pc are on same work group. Later on ill be putting or setting up passwords, but im wanting to resolve this speed problem before i start adding more settings to it.

*Note
Before people start stating its because im wireless, i thought of that too and thats not it. As i can transfer files to other hard drives through the network and i still get mixed speeds.

Also i forgot to mention this also.

I made sure on my mobo's had at least i had 2X I/O's at 6GB's for my raid1/mirror.
i5 - Z77 spec's
2 x SATA 6Gb/s connectors (SATA3 0/SATA3 1) supporting up to 2 SATA 6Gb/s devices
i7 - X79
2 x SATA 6Gb/s connectors (SATA3 0/1) supporting up to 2 SATA 6Gb/s devices

Even when transferring files on the same hard drive i dont think im getting the proper transfer rate also, im only getting roughly 20mb - 40mb speed.
As far as i know this should be almost instant if im not wrong, i have tried both CUT & PASTE and COPY & PASTE.
both are at same speeds

My Hard Drive spec's if relavent
i5-Z77 Seagate 500GB ST500DM002 16Mb Cache 7200 RPM
i7-X79 Seagate 1TB ST1000DM003 64Mb Cache 7200 RPM
Toshiba 3TB DT01ACA300 64Mb Cache 7200 RPM