Regular SD-cards actually do go up to 4GB.
SD (non-SDHC) cards with greater than 1 GB capacity
The SD Card Association's current specifications defines how a standard SD card (non-SDHC) card with more than 1 GB and up to 4 GB capacity should be designed. These cards should be readable in any SD 1.01 devices that takes the block length data into account. Any 1 GB or lesser card should always work. (So the key question is how one's reader handles block length).
According to the specification, the maximum capacity of a standard SD card is defined by (BLOCKNR x BLOCK_LEN), where BLOCKNR may be (4096 x 512) and BLOCK_LEN may be up to 2048. This allows a capacity of 4 GB. The main problem is that some of the card readers only support block (aka. sector) size of 512 bytes, so >1GB non SDHC cards may cause compatibility difficulties for some users.
Any reasonably modern device bought in the last few years should be able to read 4GB SD cards. I deliberately chose to buy a 4GB SD card for my camera and not a SDHC even though the camera supports it because I can use it with hardware I already have. I have a HP hx4700 Pocket PC with a very nice 4 inch VGA screen but it doesn't support SDHC. I have always used it with a 4GB SD-card (bought 2.5 years ago for ten times the price I bought 4GB cards for this year).
With a regular SD card in my camera I can put the SD-card directly from the camera in the Pocket PC if I want to view photos on the 4 inch VGA screen. And I still have to check whether any of my current card-readers support SDHC so I didn't have to bother about that either. Unless you shoot a lot of video a 4GB card will give you more than enough space for your photos. You won't easily fill that up in a single shooting day.
When in doubt..... Press the shutter.