For a first softmod, it's better to have a non sdhc card.
Once your wii is modded, a sdhc should work fine.
The only issue I have seen so far is bootmii @ boot2 not finding the armboot.bin file on a sdhc card.
If I run it from the homebrew channel afterwards, it detects the file correctly.
I think the card initialises to slow upon initial boot causing those issues.
If you have a card, just try it. You can't break things. The worst that can happen is that it doesn't work.