Lag in DotA

Well my game was running smoothly,before i installed windows 7... Since I got it, seems that I can't play a normal clan war with my clan... The problem is that My game runs smoothly when there aren't many creeps or heroes on the screen,but when there is a team battle or many creeps(less in this case) i get delay for 5 secs,or more.. My internet connection is same as before,and I never lagged when i had xp ...
My operative system looks like this:
Proccesor: AMD Athlon(tm) 64 proccesor 3500+ 2.20 Ghz
Installed memory(ram): 2.00 GB
System type: 32-bit operating system
And my adapter type is : Radeon X1600 series( microsoft corporation - wddm)
And its info is:
Chip type: ATI Radeon Graphics Proccesor (0x71C3)
DAC type: Internal DAC(400Mhz)
Adapter String: Radeon X1600 series
Bios information: 113-AA81702-116

I don't know much about computers that's why i posted everything... Hope you gonna help me.. :)

Even though DoTA doesn't require much in terms of system resources, running it on top of Windows 7 requires more grunt then XP did, this is why you might be seeing a decrease in system performance. You processor and GPU should be fine for DoTA. Though it would be nice if you could add some more RAM to your system. Because of the GPU i'm assuming this is a laptop?

No,actually its a regular computer...but its kinda old... All of my effects in dota,shadows etc... Is turned off...

Ohh right, thats ok then, it gives you some options. Like i said, your resources are being a bit taxed running Windows 7 instead of XP. I can think of three things you could do to improve performance:

1. Make sure there isnt many processes running in the background, things that may run on startup that arnt necessary. Follow the following guide How to Change, Add, or Remove Startup Programs in Windows 7 using Method Three-
Through System Configuration, and remove these programs.

2. Make sure you have the latest drivers for your hardware. Don't just rely on Windows 7's default drivers if you can help it.

3.Install more RAM, if this is possible i would highly recommended it, it would mean fining out what type of motherboard you have and installing compatible RAM for that mobo.

And little things like tweaking Warcraft's settings, turning everything to low if you can and just reducing your screen resolution can make a difference.

Ok,thanks I will try that but I must keep TS working while playing...Hope that wont be a problem :)

Yes i had the feeling you were running Vent or TS as well, that certainly wont help things much. Though it cant be helped with games like DoTA..i understand :)

hehe... ok I will post later if there are some changes :)