500 boxes on one net is a lot. Is there some pattern you could use to subdivide the net into smaller subnets? If it is a retail business, think about sales, accounts receivable, inventory, and shipping on their own networks. Try to keep the file sharing boxes on the same subnet with the servers that contain the files.

If the clients are all behind the same router, slow file sharing has nothing to do with the router as it isn't involved in clients on a network directly talking to one another.

If Internet surfing is slow, check whether your circuit is saturated. Several hundred clients all checking Facebook at noon during lunch breaks can bring down a fairly large circuit - investigate upgrading the circuit or implementing QoS. With that many devices on the same broadcast domain you could also run into problems on the edge of the network, which doesn't have anything to do with the router. As dove24u mentioned breaking things up into smaller networks would be one way to avoid those issues.

If the clients are all behind the same router, slow file sharing has nothing to do with the router as it isn't involved in clients on a network directly talking to one another.

If Internet surfing is slow, check whether your circuit is saturated. Several hundred clients all checking Facebook at noon during lunch breaks can bring down a fairly large circuit - investigate upgrading the circuit or implementing QoS. With that many devices on the same broadcast domain you could also run into problems on the edge of the network, which doesn't have anything to do with the router. As dove24u mentioned breaking things up into smaller networks would be one way to avoid those issues.

Thanks for your response.
I was thinking of breaking the network into subnets,But I want to ask is it feasible using MikroTik RoS(with Level 4 lic) on x86 sytem and still be able to share files and other resources.if yes How do I go about it.

Is this issue related to the other thread regarding file sharing and printing? You did not like the answer that you need a domain controller. What is the point of subnets if you want to forward broadcast?

I was thinking of breaking the network into subnets,But I want to ask is it feasible using MikroTik RoS(with Level 4 lic) on x86 sytem and still be able to share files and other resources.if yes How do I go about it.

Is it feasible to configure RouterOS as a router? Yes it is. I don't think it is likely that anyone on a forum can answer the "how do I go about it" question,because it is WAY beyond the scope of what can be described here. Maybe the question you are asking is not what I THINK you are asking.

I can tell you that in order to break a network into subnets, you just change the IP/Netmask on the devices, add one of the IPs from each subnet/range on the router and that's it. That, of course, is the most simple answer possible. Is that what you were asking about?

I was thinking of breaking the network into subnets,But I want to ask is it feasible using MikroTik RoS(with Level 4 lic) on x86 sytem and still be able to share files and other resources.if yes How do I go about it.

Is it feasible to configure RouterOS as a router? Yes it is. I don't think it is likely that anyone on a forum can answer the "how do I go about it" question,because it is WAY beyond the scope of what can be described here. Maybe the question you are asking is not what I THINK you are asking.

I can tell you that in order to break a network into subnets, you just change the IP/Netmask on the devices, add one of the IPs from each subnet/range on the router and that's it. That, of course, is the most simple answer possible. Is that what you were asking about?

@Butche,Tanx U got me write.Further suggestion welcome.

@Butche,Tanx U got me write.Further suggestion welcome.

Best suggestion is: http://www.mikrotik.com/consultants.html and pay for good help. It sounds like you need real assistance and not just rely on forum for free support. The forum is not designed to enable complete network engineering, but for answers to questions. "Build my network, please" is not a question that can be answered on a forum.