According to Wikipedia's PCI article and List of device bandwidths, PCI bus bandwidths can be calculated with the following formula:
frequency * bitwidth = bandwidth
33.33 MHz * 32 bits = 1067 Mbit/s = 133.32 MB/s
Conventional PCI buses operate with the following bandwidths:
- PCI 32-bit, 33 MHz: 1067 Mbit/s or 133.33 MB/s
- PCI 32-bit, 66 MHz: 266 MB/s
- PCI 64-bit, 33 MHz: 266 MB/s
- PCI 64-bit, 66 MHz: 533 MB/s
According to the same links:
- SATA (SATA-150): 150 MB/s
- SATA (SATA-300): 300 MB/s
- Fast Ethernet (100base-X): 11.6 MB/s
- Gig-E (1000base-X): 125 MB/s
Theoretically, it looks like you've got room on the PCI bus for two Gig-E cards, or a SATA-II card, but not both. At least, not running at theoretical maximums. If you put in all three, running them all at full load will bottleneck at the PCI bus.
Fortunately, you won't come close to hitting theoretical speeds on the SATA interface (unless you're using expensive SSD drives). Your Gig-E cards will probably come closer, but in all cases the real-world speeds will be significantly less than theoretical speeds.
I expect such a setup will work fine for many applications.