hitting SRAM limits?

I'm getting some weird behavior in my sketch when I have a long array greater than 70 elements or so with an ATMEGA8. I suspect I am running out of SRAM, is there a way I can tell for sure (some sort of reporting or calculations)?

The ATMEGA8 has 1K of SRAM. a long variable has 32 bits. So a 70 element array would be 70*32 = 2240bits = 280 bytes Am I doing the math correctly?

Thanks

Try this:
http://arduino.cc/forum/index.php/topic,118440.0.html

It is quite handy for the 168 and 328. This IDE variant calculates the SRAM usage during the compile.

I have not tested the Atmega8.

memotick:
Am I doing the math correctly?

You are doing it correctly, but other things use RAM too. Without seeing your sketch it is hard to say.