You need the best Micro SD card you can get for that kit
Slower cards = freeze ups and lag
If it does support SDHC then you want class (10)
If I remember correctly made in Japan Kingston 1GB & 2GB Micro SD's are much higher Quality and faster than Made in Taiwan Kingston 1GB & 2GD Micro SD's (The Kingston made in Japan ones are the best to go for if the kit does not support HC cards most others had issues due to being slower cards)
Also note that some games do require patching to work on those kits
Original R4 kits and clones use wood kernal (it's not firmware even though some sites do call it firmware, it would be firmware if it was flashed to a chip, but it's kernal because it runs from local storage being a Micro SD)
http://filetrip.net/nds-downloads/fl...les/r4-series/ has version 1.62 of the wood R4 kernal
http://www.trendy.co.jp/sd/en/p_formatter.html is another tool worthy of note and use that to do a qwick format of your Micro SD card
Also when you copy games over to it do that one at a time to avoid mixed up sector issues because if you have more than one copy to operation running the files mix the sectors up so you have for example 2 files, file one in sectors 1,2 & 5 and file 2 in sectors 3,4 & 6 that would result in harder reading
http://www.ds-scene.net/?s=viewtopic&nid=11056 Lastly there is DS-Scene Rom Tool that can be used to patch the games that require it aswell as tons of other things