slow transfer rates between 2 PCs

[timtheenchanter]

I have a basic network setup at home, Virgin media hub downstairs, connected to the lounge media centre (basically a XP machine connected to the TV) another connection to the loft, where it is connected to another hub (ex sky router) this in turn is connected to my main PC, the file server, and a printed.
Nothing (as far as i know) has changed, but i can no longer stream directly from the file server, and transferring data is taking an age (650Mb taking approx 30 mins)
The DNS is turned off on the sky router, and using the dns on the virgin hub, have tried restarting both hubs, and nothing has changed.
The only other things on the network are my wifes lappy, and our 2 android phones, all via wireless.
Actual internet speeds from all wired machines are approx the same, and about what we are supposed to be getting, so throughput doesn't seem to be the issue, but PC to PC data is.

Anyone got any clues, or tips to fix this (or further reading suggestions)

 

[Igorian]

How are the two routers physically connected? What speeds are the nics running at on the client and server? How much other activity is there on the other clients? What are the ping response times like between client and server? Do a trace route from the client to the server too and post the results. Are any of the disks filling up?

Has it ever worked better? If so, have there been any changes, however insignificant the might sound, been introduced?