Ethernet Shared Drive with OSX File System and NTFS Partitions

I would like to purchase an Ethernet-based external hard drive (NAS or whatever) that can be partitioned into two logical drives. One partition would have NTFS for all my windows machines, and the other would have the OSX 10.5 file system (HFS+ ??). I would use the OSX partition for time machine as well as a place to just copy files if I want to (from my MAC). I would use the NTFS partition to store backups and as a single point of storage for my other Windows-based files.

I realize I could make a big FAT32 partition for both, but FAT32 drops file attributes that exist in both NTFS and HFS+ (guessing on the latter), and it won't support really long filenames (which I use all the time in NTFS).

So, is there any such product on the market today that would support this? How about if I buy a USB HD (yuck), and put a USB hub-type-thingy off my Ethernet switch?

The reasons I want this solution:
1) My cable modem is by my TV, where I have my 4-port switch with Wireless N. I want to put the HD there so all my computers can share it, but I sure don't want to have a big desktop computer or anything like that over there (just to host HD storage).

2) I want my PCs and my MAC to have a shared drive on the network for backup, but I don't want either to have to compromise on the file system they are using (things -- attributes, etc. -- are always lost in translation going from one file system to the other).

3) I don't want to have to leave one or more laptops on so other machines can get to the files.

Any help or suggestions for other viable shared storage options would be appreciated.

Thank you.