Use this thread as a reference to help you purchase a SD card that works for Wii Hacking/Modding. Credits to the old wiihacks.com site for the original list.
You can only use SDHC (cards 4gb or higher) with system menu 4.0 or above!
Apacer: 2GB SD - Wii: Works, HBC: Works, Bootmii: Unconfirmed, Bannerbomb: Unconfirmed
DANE-ELEC: 4GB SDHC - NOT working
Kingston: 2GB Micro SD W/ Kingston adapter - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
Lexar: 1GB SD - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
Micro Center: 2GB SD (920249) - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Unconfirmed
Micro Center 4GB SDHC - Wii: Untested, HBC: Works, Bootmii: Works, Bannerbomb: Works
PNY: 1 GB SD - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
PNY 2GB class 4 Optima SD (SD-M02G) - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
PNY 8GB class 4 Optima SDHC (SD-K08G) - Wii: Works, HBC: NOT Working, Bootmii: NOT Working, Bannerbomb: NOT Working, Notes: This card appears to only be good for storing WiiWare/VC and game saves
PQ1: 2GB Micro SD/adapter - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works, Notes: Good for SNEEK
Samsung: 2GB SD - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
SanDisk: 2GB SD - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
SanDisk 2GB Ultra SD - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
SanDisk Transcend 2GB SD (TS2GSDC) - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
SanDisk 4 GB Wii/DS SDHC - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
SanDisk 4GB SDHC - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
SanDisk 4GB Micro SDHC W/ adapter - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
SanDisk 8GB Ultra SDHC - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
SanDisk 8GB Micro SDHC W/ adapter - Everything should work in theory, untested
SanDisk 16GB Ultra SDHC - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
SanDisk 16GB Micro SDHC W/ adapter - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
SanDisk 32GB Ultra SDHC - Everything should work in theory, untested
SanDisk 32GB Ultra PLUS SDHC - Everything should work in theory, untested
SanDisk 32GB Extreme PRO SDHC - Everything should work in theory, untested
SanDisk 32GB Micro SDHC w/ adapter - Everything should work in theory, untested
SanDisk SDHC (any type greater than 32GB) - WILL NOT WORK (in theory because Windows can't create FAT32 partition sizes larger than 32GB, but it could work if you use Linux GPARTED program to create the FAT32 partition)
You can only use SDHC (cards 4gb or higher) with system menu 4.0 or above!
Apacer: 2GB SD - Wii: Works, HBC: Works, Bootmii: Unconfirmed, Bannerbomb: Unconfirmed
DANE-ELEC: 4GB SDHC - NOT working
Kingston: 2GB Micro SD W/ Kingston adapter - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
Lexar: 1GB SD - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
Micro Center: 2GB SD (920249) - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Unconfirmed
Micro Center 4GB SDHC - Wii: Untested, HBC: Works, Bootmii: Works, Bannerbomb: Works
PNY: 1 GB SD - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
PNY 2GB class 4 Optima SD (SD-M02G) - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
PNY 8GB class 4 Optima SDHC (SD-K08G) - Wii: Works, HBC: NOT Working, Bootmii: NOT Working, Bannerbomb: NOT Working, Notes: This card appears to only be good for storing WiiWare/VC and game saves
PQ1: 2GB Micro SD/adapter - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works, Notes: Good for SNEEK
Samsung: 2GB SD - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
SanDisk: 2GB SD - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
SanDisk 2GB Ultra SD - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
SanDisk Transcend 2GB SD (TS2GSDC) - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
SanDisk 4 GB Wii/DS SDHC - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
SanDisk 4GB SDHC - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
SanDisk 4GB Micro SDHC W/ adapter - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
SanDisk 8GB Ultra SDHC - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
SanDisk 8GB Micro SDHC W/ adapter - Everything should work in theory, untested
SanDisk 16GB Ultra SDHC - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
SanDisk 16GB Micro SDHC W/ adapter - Wii: Works, HBC: Works, Bootmii: Works, Bannerbomb: Works
SanDisk 32GB Ultra SDHC - Everything should work in theory, untested
SanDisk 32GB Ultra PLUS SDHC - Everything should work in theory, untested
SanDisk 32GB Extreme PRO SDHC - Everything should work in theory, untested
SanDisk 32GB Micro SDHC w/ adapter - Everything should work in theory, untested
SanDisk SDHC (any type greater than 32GB) - WILL NOT WORK (in theory because Windows can't create FAT32 partition sizes larger than 32GB, but it could work if you use Linux GPARTED program to create the FAT32 partition)