[Asterisk-Users] how scalable is digium cards?

[lito lampitoc]

This might be a newbie question but I'm just wondering
how would it be possible to have 30 analog lines using asterisk for PBX
by just using TDM40B and X100P (or are there any device>), if an
ordinary PC support just 4 PCI slots? the maximum scale i guess would
just be 2 x 8.  Adding a new PC just for this purpose would be costly.

I would appreciate your comments. 

Thanks.