ms antivirus is pretty barebones but quite ok coupled with spywareblaster and a decent firewall like komodos
kaspersky goes to extremes sometimes and even disregards excluded folders if its heuristics pick up something that accesses memory (which a lot of compilers do) so i usually turn it off when building.
I just uploaded the compiler as an installer also for those not savy with making shortcuts to all the tools btw
its pretty non intrusive and does not change any system settings (the package is portable by nature) you can even run it from a USB stick if you want to.
The installer defaults to C:\CodeBlocks and cannot be changed because win 7 has protected folders like C:\ProgramFiles you would get access errors trying to compile from there.
MinGW also has problem with PATHS that have spaces in them unless you use quotes in the PATH and its a bit hairy setting that up.
It works right out of the box with the default PATH though

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Productivity is a state of mind.